ISRO SDSC SHAR 2026 Preparation Guide: Post-code Decisions, Technical Problems and Selection Gates

Imagine two candidates preparing for SDSC SHAR. One spends most evenings solving trade theory and treats the practical test as something to address after the result. The other practises workshop tasks but assumes a strong practical performance will compensate for an average written score. Both can misjudge the recruitment: in the technical group, the written paper determines ranking, while the skill test is a compulsory qualifying gate.

The challenge becomes more complicated when friends applying for different posts share a study plan. A Driver candidate has a separate Part A threshold. An MTS candidate has a different penalty and no skill-test stage in the advertised selection route. A Fireman candidate must manage certificate validity and physical stages alongside the written paper. This guide follows those decisions through worked examples, so you can build a preparation file around your own post code rather than around the broad label “ISRO exam”.

The exercises are original teaching problems. They are not previous-year ISRO questions, leaked material or predictions. Numerical models state their assumptions; practical practice suggestions are distinguished from the official test requirements.

For the complete vacancy roster, eligibility and application links, open SarkariSapna’s ISRO SDSC SHAR 2026 recruitment page. The official ISRO listing identifies the advertisement dated 19 October 2026 and the closing date of 9 November 2026. The notification specifies submission, including payment, by 23:59 on 9 November; written and skill-test dates are to be announced separately. Application instructions; examination-date notice.

📌 Map the recruitment before choosing study material

The 24 post codes run from 07 to 30. Adding their advertised vacancy counts gives 97. The grouping below is a calculation from the notification’s post tables; it is not a combined merit list. Two applicants in different trades do not compete merely because their posts appear in the same row here.

Post group	Codes	Vacancies	First eligibility check
Technical Assistant	07–11	14	Exact diploma discipline, First Class and minimum three-year duration
Scientific Assistant	12–13	3	Exact degree and subject combination
Library Assistant A	14	3	First Class graduation and prescribed First Class postgraduate library qualification
Nurse B	15	3	Prescribed nursing diploma and State Nursing Council registration
Technician B / Draughtsman B	16–25	44	Specified NCVT trade credential; read special conditions
Fireman A	26	2	Matriculation plus prescribed physical and medical requirements
LVD / HVD	27, 28, 30	12	Appropriate licence and acceptable post-licence experience
MTS	29	16	SSC/Matriculation or equivalent

Official post tables, pages 1–9. Fireman and MTS carry a normal age range of 18–25; the other codes are 18–35, assessed on 9 November 2026. Category relaxations have conditions, including the reservation against the relevant post. A higher qualification or a similar-sounding trade name does not automatically establish eligibility. Age provisions.

Read the eligibility line as a set of conditions

The most expensive preparation mistake is spending weeks on a post for which a crucial credential is missing. A post title tells you the occupation; the qualification line tells you the entry route. Read that line against your actual certificates, not the subjects you remember studying.

Technical Assistant: codes 07–11 require a First Class diploma in the specified discipline, with a minimum duration of three years. A degree holder should not assume that a degree automatically replaces the advertised diploma. The notice asks candidates claiming equivalence to provide documentary evidence certified by the university or concerned institution. That is an evidence requirement, not a blanket statement that all higher qualifications are accepted.

Scientific Assistant, Physics: code 12 specifies First Class B.Sc. with Physics as the main subject and Mathematics and Chemistry as ancillary subjects. A transcript showing Physics and Mathematics alone does not establish the complete stated combination. For code 13, the relevant First Class degree is in Fine Arts (Photography) or Visual Arts (Cinematography). General interest in photography is not the qualification.

Library Assistant: the notice requires First Class graduation as well as the prescribed First Class master’s qualification in Library Science/Library and Information Science or equivalent. Checking only the postgraduate grade misses a separate condition. Nurse: the stated route is a First Class nursing diploma of at least three years, recognised by the relevant government, with registration with the respective State Nursing Council. Do not silently substitute an unmentioned qualification route.

Technician: the trade wording matters. Electrician and Electronic Mechanic are separate codes. Chemical code 17 lists particular accepted trades; Boiler Attendant code 20 has a specific NAC and First Class Boiler Attendant certificate condition. “I studied related topics” is not the same as holding the prescribed certificate. For the full trade list, use the qualification column rather than a shortened recruitment headline.

Qualification evidence: notification pages 1–9. Build a personal evidence sheet before applying:

Condition	Evidence to inspect	An unresolved issue worth identifying early
Qualification title	Final certificate plus marksheets	A broad branch name differs from the advertised discipline
Class / grade	Official result and university conversion rule, if needed	You calculated a percentage using an unofficial formula
Course duration / subjects	Transcript and course record	Required duration or ancillary subject is not established
Trade / registration	Relevant trade certificate or registration record	Credential belongs to a different trade or registration is not established
Experience, where required	Acceptable employer certificates and licence history	Part of the claimed period predates the relevant licence

This sheet is for your own verification. It should expose gaps, not manufacture equivalence. Where the notice leaves an individual case unresolved, obtain clarification through the official recruitment channel before making a claim in the application.

Driver experience: four years on a résumé may not be four eligible years

For LVD codes 27 and 30, the notice requires three years’ experience and the appropriate valid licence. For the Driver codes, prescribed experience must follow the valid driving licence; part-time experience is excluded. Certificates should come from the listed institutional types, such as government/semi-government agencies or registered companies, societies and trusts. A certificate issued by an individual is not accepted under this clause.

Illustrative case: an applicant claims four completed years of driving work, but only two completed years fall after obtaining the relevant valid licence. Counting the entire four-year period does not establish the three-year LVD requirement. A second applicant has three post-licence years but only an individual’s certificate; the duration and the documentary acceptability are separate problems. Neither case can be resolved by a high written score.

Prepare a chronology with the licence date, employment start and end dates, full-time status, employer identity and certificate reference. Do not double-count overlapping periods. The HVD code has its own total and heavy-vehicle experience requirements, so an LVD chronology cannot be reused without checking those conditions. Driver qualifications and experience clauses, pages 6–9.

Five selection routes: keep their rules separate

Route	Written examination	Next requirement	What determines merit
Technical / Scientific / Library Assistant; Technician / Draughtsman	80 questions; 90 minutes; +1 / −0.33	Qualifying skill test, 100 marks	Written score among eligible skill-qualified candidates
Nurse B	80 questions; 120 minutes; +1 / −0.33	Qualifying skill test	Written score among skill-qualified candidates
Fireman A	80 questions; 120 minutes; +1 / −0.33	PME eligibility, PET stages and DME	Written score after required PET/medical qualification
LVD / HVD	100 questions; 120 minutes; +1 / −0.25	Qualifying driving skill test	Written score among skill-qualified candidates
MTS	100 questions; 90 minutes; +1 / −0.25	Written-test selection route	Written score, subject to eligibility and notified vacancies

Unattempted questions carry no penalty under these marking patterns. Selection rules, pages 13–20. “Qualifying” does not mean optional: failure at a required practical or medical stage prevents selection even when the written score is strong.

The technical-group minimum is not a promised shortlist score

For the group covered by section 4.1, the written minimum is 32/80 for unreserved candidates and 24/80 for reserved candidates only where the post is reserved. The corresponding skill-test minima are 50/100 and 40/100. Shortlisting is category-wise at 1:5, with a minimum of ten candidates, and candidates may be called in batches. The eventual shortlist depends on actual performance and vacancies. Do not describe 32 as the expected competitive cutoff.

The skill marks are not added to written marks for final ranking. In a hypothetical unreserved case, applicant A scores 60 in writing and 51 in skill, while B scores 57 in writing and 92 in skill. Both clear the stated skill minimum; B’s much higher practical score does not turn 57 into a higher written merit score. This example explains the rule, not the result of any actual selection.

Nurse and Fireman applicants: avoid borrowing another row’s cutoff

The Nurse section specifies its own 120-minute written paper and qualifying skill process. It does not provide the same numerical qualifying table printed under section 4.1. Similarly, the Fireman route has its own physical and medical progression. Copying the technical group’s 32/24 or 50/40 thresholds into these routes would add a rule that the relevant section does not state.

What the shortlist ratio does—and does not—tell you

For the technical group, a 1:5 ratio describes how the institution intends to call candidates relative to vacancies, subject to the category-wise minimum and batching provisions. It does not give you a probability of selection. A candidate cannot divide one by five and call the result their personal chance: the applicants’ scores, eligibility, reservation, skill performance and batch decisions are not random interchangeable events.

Nor should you multiply the overall 97 vacancies by five and present that as a universal shortlist size. The notice contains different post codes, categories and selection routes. Use the shortlist rule only within the relevant route and the institution’s actual category-wise process. A private mock rank has still less authority; it measures performance within the people who happened to take that mock.

Practical implication: keep two preparation objectives. First, make written performance competitive rather than merely equal to the minimum. Second, identify skill weaknesses early enough to improve them. Allocating no time to practical competence until a call letter arrives is a risk; letting practical sessions replace all written revision is also inconsistent with how merit is drawn.

📊 Driver preparation has two written-test gates

The Driver paper allocates half its questions to the Motor Vehicles Act. The other half covers English, arithmetic and general knowledge. Annexure I expands the topics; its legal component refers to the Act as amended. Use current official legal material when studying individual provisions rather than memorising an undated list of penalties.

Driver written paper: official distribution of 100 questions

Section	Questions
Motor Vehicles Act	50
Elementary English	15
Elementary arithmetic	15
General knowledge	20

Driver paper and qualifying rules; Annexure I syllabus. Under the general standard, candidates need at least 50% in Part A and at least 50% in Parts B, C and D combined. These are separate checks. The notice permits a conditional relaxation of written qualifying marks, up to the stated limit, when sufficient reserved-category candidates are unavailable; it is not an automatic lower threshold for every reserved applicant. The driving skill test requires at least 60% for all candidates, without the listed category relaxation.

Worked scorecard: why 62 overall can still fail the general standard

Consider this original score example. In Part A, a candidate answers 28 correctly and 16 incorrectly, leaving six blank. The net score is 28 − (16 × 0.25) = 24. In the other three parts combined, the candidate gets 40 correct and eight wrong, leaving two blank: 40 − 2 = 38. The total is 62/100, yet Part A is below 25/50. Under the general qualifying standard, the total cannot compensate for that shortfall.

This changes how a Driver mock should be reviewed. Record two net scores, not just one percentage. If your general-awareness performance improves while Part A remains weak, the overall graph can look encouraging without solving the selection problem. Keep a separate error list for licensing, registration, traffic control, insurance and other notified legal topics.

Build a Driver revision file around situations, not isolated section numbers

Annexure I names licensing, registration, control of transport vehicles, traffic control, insurance, offences and procedures, mandatory signs and accident-claim topics. A useful study file has one page for each theme. On that page, distinguish the person, the vehicle, the document and the event. A question about a driver’s licence is not answered by establishing that the vehicle is registered; a document concerning the vehicle does not prove the driver’s experience.

For each legal provision you study, record its official source, the version you read, the condition that triggers it and any stated exception. Do not learn an amount or time limit from an old coaching screenshot. This article does not reproduce a changing penalty schedule. Use the current official Act and applicable rules while following the recruitment syllabus.

Original reading exercise: a hypothetical instruction says, “Vehicles assigned to Route B may enter the service area only after the supervisor records clearance.” Which conclusion follows? (A) Every Route B vehicle already has clearance. (B) Clearance is required before entry. (C) Other routes never require clearance. (D) The driver may record the supervisor’s approval later. Answer: B. The sentence sets a prerequisite. It does not confirm that any specific vehicle has met it, and it says nothing about every other route. This tests conditional reading, not an actual traffic rule.

For arithmetic, combine units and records. If a schedule states kilometres, minutes and litres, write the requested output unit before calculating. For English, practise selecting a verb or phrase that preserves the condition in the sentence; a grammatically smooth option can still change its meaning.

MTS: use the notification’s detail, and recognise its limits

MTS covers numerical and mathematical ability, reasoning and problem solving, general awareness, and English language and comprehension. The notice gives 100 questions in 90 minutes but does not allocate 25 questions to each subject. An equal four-way split may be a practice design; it should not be advertised as the official blueprint.

The minimum qualifying percentages are 50 for UR/EWS, 45 for OBC and 40 for other reserved categories against notified reserved vacancies. Ranking still depends on the available seats. The stated tie sequence is reasoning/problem-solving marks, followed by date of birth with the older candidate placed higher. That gives you another reason to record subject performance rather than keeping only the final mock score.

An MTS reading problem that rewards restraint

Passage: “Of 120 requests received during the month, 84 were completed by the reporting date. Twelve of the remaining requests awaited documents from applicants. The report does not state why the other requests remained open.” Which statement is supported?

(A) Thirty-six requests were rejected. (B) All pending work was delayed by applicants. (C) Twenty-four requests remained open for reasons not specified in the passage. (D) The office completed 84% of requests.

Answer: C. Pending requests = 120 − 84 = 36. Of these, twelve have a stated reason, leaving 24 with an unspecified reason. Pending is not rejected. The completion proportion is 84/120 = 70%, not 84%. The question combines arithmetic with the discipline of not inventing a cause. In a timed paper, underline “received”, “completed” and “remaining” before choosing the denominator.

Negative marking: diagnose the mistake before changing your attempt count

For the 80-question technical paper, use the printed penalty of 0.33 in your practice calculation. Do not quietly substitute an exact one-third and then compare differently calculated scores. The following results are hypothetical; each includes all 80 questions as correct, wrong or blank.

Mock	Correct	Wrong	Blank	Net score
A	48	24	8	40.08
B	54	12	14	50.04
C	58	16	6	52.72

Illustrative technical mock scores after the printed 0.33 penalty

0204060Net score ↑40.08AA: 40.08 Net score50.04BB: 50.04 Net score52.72CC: 52.72 Net score

Select a column to see its exact value.

Mock	Net score
A	40.08
B	50.04
C	52.72

Mock B has fewer attempts than A but a higher score. Mock C then improves on B while attempting more questions. Neither “attempt everything” nor “always attempt less” explains both changes. The useful question is which additional answers you can make reliably.

Classify every wrong answer into one of four causes: missing concept, wrong model, calculation error or misreading. Re-reading a chapter helps the first cause. It may do little for the third if you repeatedly lose a decimal point under time pressure. Record the correction alongside the question: “converted millimetres to metres before squaring” is more actionable than “careless mistake”.

The score behind an answer changed at the last minute

For the technical marking pattern, changing a wrong answer to a correct one changes the score by 1.33: you remove a 0.33 penalty and gain one mark. Changing a correct answer to a wrong one loses the same 1.33. This is why the review stage should be driven by a discovered error—wrong unit, overlooked condition or corrected calculation—not simply by anxiety about an option.

Imagine that a mock review changes six wrong answers to correct and four correct answers to wrong. The net benefit is (6 − 4) × 1.33 = 2.66. The count “ten answers reviewed” says little by itself. Keep a small review log for a few mocks and identify whether your changes improve decisions or merely add noise.

There is no guaranteed attempt count. A probability calculation also depends on assumptions about your chance of being correct, time cost and the penalty. If you do not know those inputs, a confidently stated universal target is not analysis. Use your own topic-level performance and the actual paper instructions.

🔧 Technical practice: show the reasoning, not just the option

The following exercises sample underlying skills. They are not a complete syllabus for any trade, and applicants should select only those relevant to their qualification. Use your prescribed course material to extend each problem into a small set of variations. For practical tasks, follow the institution’s equipment and safety procedures; these paper exercises are not instructions to work on live equipment.

1. Fitter and mechanical measurement: a reading close to the limit

A fictional drawing accepts a diameter from 20.00 mm to 20.04 mm inclusive. A measured indication is 20.03 mm. The instrument has a positive zero error of 0.02 mm, meaning that it reads 0.02 mm when the true input is zero. What corrected value should be compared with the drawing?

Answer: corrected value = indication − zero error = 20.03 − 0.02 = 20.01 mm. On the simplified information supplied, it is within the stated limits. Adding the positive error would produce 20.05 mm and an incorrect rejection. In actual inspection, calibration, uncertainty and the specified acceptance procedure matter too; this question isolates the sign convention.

Make it harder: change the zero error to −0.02 mm. The corrected value becomes 20.05 mm. If your answer remains 20.01, you have memorised “subtract 0.02” instead of understanding what a signed error represents.

2. Electrical reasoning: the branch current is not the source current

In an ideal circuit, a 6-ohm resistor and a 3-ohm resistor are connected in parallel across a 12-volt DC source. Find both branch currents and the total current. Ignore wire resistance and all component tolerances.

Answer: each branch has 12 V across it. The currents are 12/6 = 2 A and 12/3 = 4 A, giving a total of 6 A. The equivalent resistance is 12/6 = 2 ohms. A useful cross-check is that a parallel combination of positive resistances must be below the smallest branch resistance here. An answer of 9 ohms indicates that the circuit was treated as series.

Now ask for total power: 12 × 6 = 72 W, which also equals 12²/6 + 12²/3 = 24 + 48. Solving the same quantity through two valid routes is a good way to detect arithmetic errors during revision.

3. Electronics: the measurement changes the circuit

An ideal 10 V source feeds two 10-kilohm resistors in series. The unloaded midpoint voltage is 5 V. A measuring instrument with an input resistance of 10 kilohms is then connected across the lower resistor. What does the simplified model predict?

Answer: the lower resistor and instrument form a parallel pair of 5 kilohms. The measured voltage is now 10 × 5/(10 + 5) = 3.33 V approximately. The 5 V answer ignores loading. This is a stronger learning exercise than recalling the voltage-divider formula alone because it requires redrawing the equivalent circuit before applying the formula.

The calculation does not assert that a particular real instrument has that input resistance. The value is deliberately chosen for the exercise. In practice, the instrument specification must supply it.

4. Turner: speed and feed are different quantities

For a paper calculation, a 40 mm diameter workpiece is assigned a cutting speed of 25 metres per minute. Use N = 1000V/(πD), with π = 3.1416. Then find feed per minute if the selected spindle speed is 200 rpm and feed is 0.15 mm per revolution.

Answer: N = 25,000/(3.1416 × 40) ≈ 198.94 rpm. At 200 rpm, the feed rate is 200 × 0.15 = 30 mm/min. A 60 mm cutting length would take two minutes under a simplified constant-feed model that excludes approach, overtravel and setup. The model assumptions are part of the answer; 200 rpm is not a universal machine-setting recommendation.

5. Civil drawing: a scale factor must match its units

A plan at 1:50 shows a rectangular room as 96 mm by 72 mm. Calculate the real dimensions and floor area, assuming the drawing is reproduced at its intended scale.

Answer: 96 × 50 = 4,800 mm = 4.8 m; 72 × 50 = 3,600 mm = 3.6 m. Area = 4.8 × 3.6 = 17.28 m². Multiplying the drawing area by 50 rather than 50² is the common error. If a drawing has been resized when printed, use the stated dimensions and scale-verification method rather than trusting a ruler measurement blindly.

6. Computer science: determine whether a dependency permits concurrency

Task A takes 4 units of time. Tasks B and C both depend on A and take 6 and 3 units respectively. Task D takes 2 units and can start only after both B and C finish. With enough resources to run B and C simultaneously, what is the earliest completion time?

Answer: 4 + max(6, 3) + 2 = 12 units. The sum of every duration, 15, assumes serial execution unnecessarily. An answer of 9 assumes D can begin before B is complete. Sketching dependencies prevents both errors. As a variation, allow only one resource for B and C; now the total becomes 15. State which resource model you are using.

7. Photography: equivalent exposure does not mean the same picture

For a simplified exposure exercise at fixed ISO, start at f/8 and 1/125 second. If the aperture changes to f/11, what shutter time approximately compensates for the one-stop reduction in light?

Answer: approximately 1/60 second, using standard marked shutter values. Doubling exposure time compensates approximately for one stop. The images can still differ in motion blur and depth of field. A question asking for equivalent exposure is not asking whether every visual property stays unchanged.

8. MTS and Driver arithmetic: remove the unsuitable record first

A practice log contains three completed trips: 120 km using 8 litres, 90 km using 6 litres, and 150 km using 10 litres. A fourth row is a planned trip of 100 km with no fuel record. Find the observed fuel efficiency for completed trips only.

Answer: total observed distance = 360 km; fuel = 24 litres; efficiency = 15 km/litre. Including the planned 100 km creates 460/24 and a false improvement. The lesson is to identify valid observations before calculating. In a second exercise, give the trips different efficiencies and compare total-distance/total-fuel with the unweighted average of trip efficiencies.

Extend the technical exercises into diagnosis and design

The earlier questions establish a model and calculate an answer. The next set asks you to choose a model, recognise a limit or explain why a tempting answer is incomplete. These are paper exercises; they do not prescribe equipment operation.

9. Fits and limits: distinguish a clearance fit from a transition fit

A fictional assembly has a hole between 25.000 and 25.021 mm and a shaft between 24.980 and 24.993 mm. Find the minimum and maximum clearance.

Solution: minimum clearance pairs the smallest hole with the largest shaft: 25.000 − 24.993 = 0.007 mm. Maximum clearance pairs the largest hole with the smallest shaft: 25.021 − 24.980 = 0.041 mm. Both are positive, so this simplified specification always provides clearance. Subtracting the two minimum values produces neither the minimum nor the maximum clearance.

Variation: keep the hole limits but change the shaft to 25.010–25.030 mm. Minimum hole minus maximum shaft is −0.030 mm; maximum hole minus minimum shaft is +0.011 mm. Depending on actual sizes, interference or clearance is possible. That is the reasoning behind classifying this simplified case as a transition fit. Naming the fit without checking the extreme pairings is a fragile shortcut.

10. AC power: apparent power is not real power

A stated single-phase sinusoidal load takes 10 A rms at 230 V rms with a power factor of 0.8. Calculate apparent and real power, and the real energy used over three hours if the conditions remain constant.

Solution: apparent power S = VI = 2,300 VA. Real power P = VI × power factor = 1,840 W = 1.84 kW. Energy = 1.84 × 3 = 5.52 kWh. Reporting 2.3 kW treats power factor as one. Reporting 5.52 kW confuses power with energy. The supplied values define a classroom model; a real installation requires its own measurements and operating conditions.

On your correction sheet, write the distinction in a sentence: “VA uses voltage and current magnitudes; real power also reflects their phase relationship in this model.” That explanation is more durable than memorising a numerical substitution.

11. Chemical trade reasoning: concentration must use the same basis

For a hypothetical mixture calculation, 200 kg of solution contains 10% solute by mass. How much pure solvent must be added to obtain 8% solute by mass? Assume no loss, reaction or evaporation.

Solution: initial solute mass = 200 × 0.10 = 20 kg. Solute remains 20 kg, so final mass must be 20/0.08 = 250 kg. Add 250 − 200 = 50 kg of solvent. Adding 2% of the initial mass would not produce the target concentration because the denominator also changes.

The result is a mass, not a volume. Converting it to litres requires density information, which is not supplied. A good answer stops at the supported unit. Actual chemical handling requires the approved substance-specific procedure; this exercise concerns conservation of mass only.

12. Refrigeration: a COP above one is not a claim of free energy

In an idealised steady operating record, a refrigeration system removes heat at 6 kW while taking 2 kW of work input. Determine its coefficient of performance and the heat rejected, assuming this is the only work input and ignoring other losses.

Solution: refrigerator COP = useful cooling/work input = 6/2 = 3. The heat rejected is 6 + 2 = 8 kW. COP is a ratio for moving heat, not the thermal efficiency of a heat engine. Calling it “300% efficient” without identifying the quantity invites confusion. If the question instead asks for heat-pump COP on this same idealised boundary, useful heating is 8 kW and the ratio is 8/2 = 4.

Check the boundary before substituting values. If a later problem supplies an additional fan input outside the original boundary, you must decide whether the requested system COP includes it. The same formula can produce different valid results for differently defined systems.

13. Physics: combine independent uncertainties using the stated model

A hypothetical resistance is obtained from R = V/I. Measurements give V = 10.0 V with standard uncertainty 0.1 V, and I = 2.00 A with standard uncertainty 0.02 A. Assume independent small uncertainties and use first-order root-sum-square propagation.

Solution: R = 5.00 ohms. Each relative standard uncertainty is 1%. Their combination is √(0.01² + 0.01²) ≈ 0.01414, or 1.414%. The corresponding resistance standard uncertainty is about 0.0707 ohm, giving approximately 5.00 ± 0.07 ohms under the stated model. Simply adding to 2% answers a different, conservative worst-case style of question, not the specified independent standard-uncertainty calculation.

The key phrase is the uncertainty model. A question giving maximum bounds, correlated errors or expanded uncertainty needs different treatment. Do not attach a confidence level to the result unless the required distribution and coverage information are supplied.

14. Electronics and computing: a timing chain can fail without an arithmetic error

A fictional acquisition system produces one record every 20 milliseconds. Processing each record takes 25 milliseconds on a single worker, and no records are discarded. Can it sustain the input indefinitely without a growing queue?

Solution: arrival rate is 1/0.020 = 50 records per second. Service capacity is 1/0.025 = 40 records per second. Backlog grows by approximately ten records per second under the simplified steady model. A larger buffer delays overflow but does not repair the long-run rate mismatch.

This is useful reasoning practice because “add memory” appears plausible until rates are compared. Changing the model to two workers introduces a new question: can the work actually be parallelised, and are there shared bottlenecks? Do not claim doubled throughput merely because two workers are present.

Turn trade revision into a practical notebook

The notification says the technical written test examines both theoretical and practical knowledge. It does not publish a station-by-station skill-test task list. The preparation grid below is an editorial exercise design, not an official list of ISRO practical tasks. Use relevant equipment only in an appropriate training setting.

Stream	Useful practice product	What to explain after completing it
Fitter / Mechanical	Inspection sheet with nominal size, limits, indication and correction	Why the instrument and comparison limits were appropriate
Electrician / Electronic Mechanic	Paper circuit model with expected values and a fault hypothesis	Which observation distinguishes the competing causes
Turner	Machining calculation sheet with units and assumptions	How diameter, speed and feed affect the calculation
Civil / Draughtsman	Dimensioned drawing interpretation and quantity worksheet	Which dimensions are supplied and which cannot be inferred
Chemical / R&AC	Mass or energy balance on a clearly drawn boundary	What is conserved and what assumptions were needed
Computer Science	Dependency / rate / data-validation exercise	Why the proposed change addresses the bottleneck
Photography	Paired images or a paper exposure comparison	Which visual change follows from the chosen setting

For every completed exercise, keep the input, output and one rejected explanation. For example: “The reading was corrected for zero error; I rejected adding the error because the instrument already over-read.” This builds an evidence-based explanation you can reproduce without memorising a paragraph.

Official learning starting points include the DGT CTS Fitter curriculum, DGT’s Bharat Skills trade resources and NPTEL’s Mechanical Measurements and Metrology course. Match the resource to your trade and qualification. A broad engineering course can deepen a weak concept, but it does not replace the prescribed curriculum or create an official chapter-weightage list.

Library Assistant: retrieval quality is a measurable skill

A library preparation plan should move beyond memorising abbreviations. Practise how a search changes when a user supplies a topic, an exact title, an edition or an author. Then identify which fields distinguish records that look similar. The following is a fictional retrieval exercise, not an assertion about any particular cataloguing standard.

15. Retrieval case: a test collection contains 40 documents relevant to a specified question. Search A returns 30 documents, of which 24 are relevant. Calculate precision and recall.

Solution: precision is the proportion of retrieved items that are relevant: 24/30 = 80%. Recall is the proportion of all relevant items retrieved: 24/40 = 60%. There are six irrelevant retrieved items and sixteen relevant items missed. Swapping the denominators swaps the meaning of the metrics.

Now Search B returns 50 documents, including 32 relevant ones. Precision is 32/50 = 64%; recall is 32/40 = 80%. Which search is “better”? The numbers alone do not answer without a task objective. A user who must avoid missing relevant evidence may value recall differently from someone who needs a short, highly focused reading list. Explain the trade-off before recommending a search.

Fictional retrieval	Relevant retrieved	All retrieved	Precision	Recall
Search A	24	30	80%	60%
Search B	32	50	64%	80%

Record comparison drill: two records share a title and author but show different edition statements and publication years. List the fields you would inspect before treating them as duplicate descriptions. Do not merge on title alone. This is a reasoning task about evidence in records; consult the cataloguing standard taught in your course for formal treatment.

Nurse: practise professional reasoning within the prescribed curriculum

For this stream, the preparation file should follow the recognised nursing curriculum and practical competencies, rather than a general technical question bank. The Indian Nursing Council’s programme guidance is an official starting point for locating the relevant framework; it is not an ISRO question-distribution document. Use your approved course texts and supervised skills training for clinical subjects.

A useful non-clinical exercise is to reconcile a fictional handover record without guessing missing information. Suppose the header identifies training record N-204, the attached sheet identifies N-240, and the time on one entry is unreadable. Write down the discrepancy, the source that must be checked and what cannot yet be concluded. Do not “correct” the identifier by assuming which sheet looks more likely. This trains document accuracy without pretending to give a patient-care protocol.

For academic case review, separate the facts supplied, the assessment requested, the applicable course concept and the evidence supporting your answer. When a question asks for priority, explain the reasoning in the context given rather than repeating an isolated mnemonic. Practical preparation should be assessed by an appropriately qualified instructor; a recruitment article cannot certify clinical competence or provide a complete treatment protocol.

Fireman: treat the medical and physical requirements as their own project

The notice requires the prescribed Preliminary Medical Examination certificate with the application. It must be issued by the specified government medical officer, is valid for six months and must remain valid at PET. A general fitness note is not automatically the required Annexure A certificate. Stage I PET precedes Stage II; failing an event disqualifies the candidate from the remaining events. Final progression also requires DME.

Fireman selection sequence; PME form; physical standards and PET tables. Annexure C separates age and gender groups. For the up-to-40 group, Stage I lists 1,500 m in seven minutes for men and 800 m in four minutes for women/transgender candidates. Those above-40 columns are standards in the annexure, not permission to ignore the advertisement’s age eligibility.

Check every applicable event and certificate field before planning practice. Rope climbing and loaded carries should be practised only with suitable facilities and competent supervision. A written-exam study schedule cannot establish medical fitness or replace the prescribed assessment. Keep the certificate date, issuing designation, applicable standards and reporting instructions together, so an administrative oversight does not undo months of preparation.

What the up-to-40 PET table actually requires

The following reproduces the event requirements in paraphrased form for the up-to-40 age column only. It is a reference for checking your applicable requirements, not a training prescription. Medical standards are separate and remain essential.

Stage / event	Men, up to 40	Women / transgender, up to 40
Stage I run	1,500 m within 7 minutes	800 m within 4 minutes
Stage II rope climb, hands only	5 m from ground level	4.5 m from ground level
Human dummy carry using Fireman’s lift	60 kg dummy; 25 m within 60 seconds	50 kg dummy; 25 m within 75 seconds
Long jump, best of three attempts	3.8 m	3.5 m
100 m run	Within 15 seconds	Within 17 seconds

Annexure C prohibits spiked shoes for the marked running events. It also contains a separate above-40 table; use that table only where it is applicable to an otherwise eligible candidate. Do not interpret one completed event as qualification for the entire PET.

Set up a record with separate columns for event, applicable threshold, supervised practice observation and the point needing improvement. Avoid combining the events into an invented total score: the advertised test is go/no-go. If an event has not been safely assessed, mark it unassessed rather than assuming that general fitness covers it. Annexure C event table.

Fee refunds: budget for the payment you must make now

Codes	Upfront payment per application	Refund: exempt group, if appearing	Refund: other candidates, if appearing
07–15	₹750	₹750	₹500
16–30	₹500	₹500	₹400

The exempt group listed for full refund comprises women, SC/ST, PwBD and ex-servicemen. Attendance at the written test is required for the stated refunds; absence does not produce a refund. Official fee/refund clause. The lower-band paragraph contains a mismatch between its numeric ₹500 and the amount spelled out in words. The ₹500 full-refund and ₹400-after-₹100-deduction entries support the numeric amount; check the official payment screen and seek clarification if it differs.

Someone applying for two eligible post codes must account for two applications and two fees. A refund later does not reduce the cash needed at submission. Enter bank details carefully and preserve confirmation records. Passing an examination and attending it are different conditions; the notification links this refund to attendance, not selection.

Location preference is a decision to make before the result

Some codes cover more than one location. Physics code 12 includes Sriharikota and Balasore; codes 10, 16, 17, 18 and 19 include Sriharikota and Rasayani. Code 20 is identified for Rasayani and code 30 for ADRIN, Secunderabad. For the specified multi-location codes, allotment follows merit-cum-preference subject to suitable vacancies. The notice does not give a selected candidate a right to demand another location later, including a vacancy caused by someone else not joining.

Prepare your preference order using a realistic view of relocation, household commitments and work requirements. It is not an estimate of which location will have the lowest cutoff. All-India transfer liability also applies under the notice. Keep location preference separate from the question of whether your exact qualification and reservation category match the code.

What vacancy concentration can tell you—and what it cannot

Fitter has 17 advertised vacancies, Electronic Mechanic 12 and MTS 16. Together they account for 45 of 97, approximately 46.4%. This is a description of the advertised distribution, not an estimate of an individual’s selection prospects. The applicant pool and category-wise competition are not supplied by these vacancy counts.

For a candidate genuinely eligible for more than one code, the comparison should start with qualification fit, practical competence, acceptable location and the separate application requirement. Choosing a trade solely because its total is larger ignores the qualification and reservation gates. Conversely, dismissing a one-seat code as “impossible” invents a competition forecast without the applicant data.

Horizontal identification must not be added again to the vertical totals. The notification’s PwBD and ex-servicemen notes describe how specified vacancies are identified or treated, not an extra block of posts on top of 97. Read the complete roster for the code before deciding which provisions apply to your application.

Six application questions worth resolving before submission

Can a fee-exempt candidate skip the upfront payment? The notice’s refund arrangement requires the stated processing payment from all candidates and returns the relevant amount subject to its conditions. Exemption from the retained application-fee component is not the same as paying nothing at registration.

Can a strong skill score compensate for fewer written marks? Not under the technical, Nurse or Driver merit structures described here. The relevant skill stage must be passed, but its marks are not added to written merit.

Can a reserved applicant assume every relaxed threshold applies? No. Check the wording against the relevant reserved vacancy and selection route. The Driver written relaxation is conditional, while its skill minimum explicitly has no listed category relaxation.

Can a preferred location be demanded after selection? The specified multi-location codes use merit-cum-preference subject to suitable vacancies, and the notice restricts claims to another location after allotment. A preference is not a guarantee.

Does an admit card settle eligibility? No. The notice permits examination participation based on application details and requires original evidence at the relevant verification stage. Keep the underlying certificates, not just the application printout.

Is the examination date fixed by the application deadline? No. The notification states that written and skill-test dates will be communicated separately. Do not turn a proposed study calendar into an announcement of an official exam date.

A mock-review routine that produces a useful next session

After a timed paper, spend the first review pass on questions you got wrong with high confidence. These are expensive because they may repeat until the underlying model changes. In the second pass, revisit slow correct answers. Look for an avoidable computation or a missing sketch. In the third, inspect blanks: distinguish an unfamiliar concept from a solvable question you never reached.

Choose the next session from that diagnosis. A technical applicant who misreads tolerances needs measurement problems with signed errors and limits. A Driver applicant below the Part A threshold needs focused legal-topic revision, not another full paper that hides the weakness inside a total. An MTS applicant losing time in comprehension should compare evidence in the passage before choosing between plausible options.

Keep a short record with the post code, mock date, applicable marking formula, correct/wrong/blank counts, net score and the two errors you will retest. The objective is not to collect dozens of scores. It is to make the next answer more reliable and to remain eligible for every subsequent stage.

Before applying, revisit the SDSC SHAR post-wise recruitment details on SarkariSapna and compare your selected code with the official advertisement. For examination updates and amendments use the official SDSC recruitment portal. Read instructions for your own code each time; a rule from another post can look familiar and still be the wrong one.