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CSAT — Paper II – Complete Study Notes

UPSC CSE Prelims Qualifying Paper

Complete Study Notes for UPSC CSE Prelims Qualifying Paper

Ch 1 · Comprehension Ch 2 · Logical Reasoning Ch 3 · Analytical Ability Ch 4 · Basic Numeracy Ch 5 · Data Interpretation Ch 6 · Strategy & Decision Making Quick Revision
1Reading Comprehension►

Reading Comprehension is the largest section in CSAT — typically 20–25 questions from 4–5 passages. It is also the most scoring section for well-prepared candidates. Master passage types, question types, and active reading strategies.

CSAT Comprehension — Key Numbers

AspectDetails
Typical passages4–5 passages per paper; 200–400 words each; bilingual (English + Hindi)
Questions per passage4–6 questions
Total comprehension questions~20–25 (out of 80 total CSAT questions)
Passage topicsSocial issues, environment, governance, science, philosophy, economics, history
Language of passageBilingual (English and Hindi provided); answer in any language you attempt

Types of Comprehension Questions

Question TypeHow to Approach
Factual / Directly statedAnswer explicitly in passage; scan for keywords; do not infer beyond text
Inference / Implied meaningNot stated but logically follows; must be grounded in passage; avoid over-inference
Central idea / Main themeWhat is the passage primarily about? Eliminate options that are too narrow (one detail) or too broad
Author's tone / AttitudeHow does the author feel about the subject? Critical / supportive / neutral / analytical / concerned
Title of passageBest title = captures main theme; not too narrow or specific; not too broad
Vocabulary in contextWhat does underlined word mean in THIS context? Choose option that fits the sentence meaning
"Which statement is NOT correct?"Reversal question; check each statement against passage carefully; do not rely on general knowledge

Active Reading Strategy

  • Step 1 — Skim the questions first: know what to look for before reading the passage; saves time
  • Step 2 — Read the passage actively: underline key sentences; mark topic sentences of each paragraph; identify the author's argument
  • Step 3 — Identify passage structure: Is it argumentative, descriptive, analytical, narrative? Know the flow
  • Step 4 — Answer from passage only: UPSC comprehension tests reading ability, not your general knowledge. "According to the passage" = look only in passage
  • Time allocation: spend 6–8 minutes per passage (read + answer); do not exceed 10 minutes on a single passage

Common Traps in Comprehension

  • Too extreme: options using "always", "never", "only", "all" are usually wrong unless passage explicitly says so
  • Outside knowledge: an option may be true in real life but NOT stated in the passage — reject it
  • Partially correct: options that are half-right; always check the entire option against the passage
  • Paraphrasing trap: correct answer is often a paraphrase of the passage, not a word-for-word copy; do not reject paraphrased options
Key: Read questions BEFORE the passage. Answer strictly from passage — not general knowledge. Comprehension = ~25 questions; highest time investment. Tone questions: look for emotional/attitudinal language in passage. "NOT correct" questions: verify each statement individually.
2Logical Reasoning►

Logical reasoning covers syllogisms, blood relations, coding-decoding, direction problems, series, and analogies. These are formula-based topics — master the rules and practise to build speed and accuracy.

Syllogisms

  • Two or more statements (premises) → conclusion; test if conclusion logically follows
  • Venn Diagram Method: draw all possible overlapping diagrams; conclusion must be true in ALL valid diagrams
  • Standard forms:
    • All A are B → A is entirely inside B
    • No A is B → A and B are completely separate
    • Some A are B → A and B partially overlap
    • Some A are not B → part of A is outside B
  • Key rule: "Some" = at least one (could be all); "No" = zero; "All" = 100%
  • If two particular premises → no definite conclusion
  • If two negative premises → no definite conclusion

Blood Relations

  • Always draw a family tree; use M (male) / F (female) notation
  • Key terms: Sibling = brother/sister; Spouse = husband/wife; In-law = spouse's relatives
  • "A is the father of B's son" → B's son has A as father → A is B's husband OR B is A's son
  • Typical UPSC format: "Pointing to a photograph, X says..." — draw the chain step by step

Coding-Decoding

TypeApproach
Letter shiftingFind the shift pattern (+2, −3, etc.); apply consistently; check if same shift for all letters
Position reversalDELHI → IHLED; check if word is reversed
Number-letter codingA=1, B=2 ... Z=26; or A=26, B=25 (reverse); identify the pattern
Symbol codingEach letter replaced by symbol; find pattern from given example
Conditional codingRules given (e.g., vowels coded differently from consonants); apply each rule

Directions

  • Draw a compass: North = up, South = down, East = right, West = left
  • Left turn from North = West; Right turn from North = East
  • Shadow problems: Morning sun = East → shadow falls West; Evening sun = West → shadow falls East
  • After turns: always mentally rotate yourself; use arrows to track direction after each turn
  • Distance: use Pythagoras theorem for net displacement (a² + b² = c²)

Series Completion

  • Number series: find the rule (arithmetic progression, geometric progression, squares, cubes, differences of differences)
  • Letter series: find gap between letters (Z=26, A=1); look for +2, −3, alternating patterns
  • Mixed series: alternating patterns; check odd and even position elements separately
  • For complex series: find difference between consecutive terms; if not constant, find second-order differences
Key: Syllogisms → always use Venn diagrams; check ALL valid diagrams. Blood relations → draw family tree first. Directions → draw compass; use Pythagoras for distance. Series → find differences first, then second-order differences if needed. Coding → look for consistent shift pattern.
3Analytical Ability►

Analytical ability covers arrangement puzzles, statement-assumption/conclusion questions, cause-effect, and argument evaluation. These require careful, structured reasoning — rushing leads to errors.

Arrangement Problems

  • Linear arrangement: people seated in a row; draw a row and fill positions using clues; eliminate impossible positions
  • Circular arrangement: people around a table; fix one person (reference); relative positions matter, not absolute; clockwise vs anticlockwise
  • Strategy: list all clues → start with definitive clues (A is at extreme left) → then relative clues (B is immediately right of C)
  • Floor/Building problems: people on different floors; use a vertical table; "above" = higher floor number

Statement — Assumption

  • Assumption: an unstated premise taken for granted by the speaker; something the statement implicitly relies upon being true
  • Test: "Does the statement make sense WITHOUT this assumption? If No → it IS an assumption"
  • Implicit assumption must be:
    • Not explicitly stated (if stated, it's not implicit)
    • Necessary for the statement/argument to hold
    • Not too far-fetched or extreme
  • Example: Statement = "Take bus Route 5 to reach the station." Assumption = Route 5 bus goes to the station (obvious, unstated necessity)

Statement — Conclusion

  • Conclusion: something that logically follows from the given statements; must be supported by ALL the statements, not just one
  • A conclusion is NOT a conclusion if: it goes beyond what the statements say; it contradicts any statement; it requires additional external information
  • Difference from assumption: Assumption is INPUT (taken for granted); Conclusion is OUTPUT (logically derived)

Statement — Argument (Strong vs Weak)

  • Strong argument: directly related to the question; not based on emotions; practical and important; addresses the core issue
  • Weak argument: trivial; based on emotion or prejudice; not directly related; hypothetical; attacks a minor aspect
  • Key test: "Is this argument substantial and directly relevant to the central issue?"

Cause and Effect

  • Two statements given; decide: I is cause & II is effect; II is cause & I is effect; both are independent; both are effects of a common cause; both are causes of a common effect
  • Look for temporal sequence (which came first), logical mechanism (does A plausibly cause B?), and scope match
Key: Arrangements → draw and fill step by step. Assumption = unstated necessity; test by removing it. Conclusion = what logically follows; must not go beyond statements. Strong argument = directly relevant, practical, substantial. Cause-effect → identify temporal sequence and mechanism.
4Basic Numeracy►

Basic numeracy covers percentages, ratios, profit-loss, time-speed-distance, averages, and simple/compound interest. These follow standard formulae — know them cold, practise mental calculations, and learn shortcuts to save time under exam conditions.

Percentages

x% of y = (x × y) / 100  |  % change = (Change / Original) × 100
If A is x% more than B: A = B × (1 + x/100)
If A is x% less than B: A = B × (1 − x/100)
Successive changes: +a% then +b% → net change = a + b + ab/100
  • Fraction-Percentage equivalents (memorise): 1/8=12.5%, 1/6=16.67%, 1/5=20%, 1/4=25%, 1/3=33.33%, 3/8=37.5%, 1/2=50%, 2/3=66.67%, 3/4=75%
  • If price increases by r%, quantity must decrease by r/(100+r) × 100% to keep expenditure constant

Ratios and Proportions

If a:b = m:n, then a = km, b = kn for some k
Componendo: (a+b)/(a−b) = (m+n)/(m−n)
If a/b = c/d, then (a+c)/(b+d) = a/b = c/d (Alternendo/Componendo)
  • Mixture problems: use alligation to find ratio of mixing two quantities
  • Alligation: |Higher price − Mean price| : |Mean price − Lower price| = parts of lower : parts of higher

Profit and Loss

Profit % = (Profit / CP) × 100  |  Loss % = (Loss / CP) × 100
SP = CP × (100 + P%) / 100  |  CP = SP × 100 / (100 + P%)
Discount % = (Discount / Marked Price) × 100
If shopkeeper uses false weights (claims W but gives W−e): Profit % = e / (W−e) × 100

Time, Speed and Distance

Distance = Speed × Time  |  Average Speed = Total Distance / Total Time (NOT average of speeds)
Relative speed: same direction = S₁ − S₂; opposite direction = S₁ + S₂
Train crossing: Time = (Length of train + Length of object) / Speed
Boats: upstream speed = B − R; downstream = B + R (B = boat speed, R = river speed)
  • Convert km/hr to m/s: multiply by 5/18  |  m/s to km/hr: multiply by 18/5

Simple and Compound Interest

SI = P × R × T / 100  |  A = P + SI
CI: A = P × (1 + R/100)ⁿ  |  CI = A − P
CI − SI (for 2 years) = P × (R/100)²
Effective annual rate for half-yearly compounding: A = P × (1 + R/200)²ⁿ

Averages

Average = Sum of observations / Number of observations
If n numbers, average = A: new number added = x, new average = (nA + x) / (n+1)
Weighted average = (w₁x₁ + w₂x₂ + ...) / (w₁ + w₂ + ...)

Work and Time

If A completes work in a days, A's 1-day work = 1/a
A and B together: 1-day work = 1/a + 1/b; time = ab/(a+b)
Pipes: filling pipe = +; emptying pipe = −; net rate = sum of individual rates
Efficiency ratio = inverse of time ratio (faster worker has higher efficiency)
Key: Average speed = total distance ÷ total time (NOT average of speeds). CI–SI for 2 years = P(R/100)². Alligation for mixture problems. Convert km/hr ↔ m/s using ×5/18 or ×18/5. Successive % change: a + b + ab/100. Work: 1-day work = 1/time; combined = sum of individual rates.
5Data Interpretation►

Data Interpretation (DI) accounts for 10–15 questions in CSAT. Questions are based on bar charts, pie charts, line graphs, and tables. Speed in reading data and quick mental calculations are the keys — not complex concepts.

Types of DI Charts

Chart TypeBest ForCommon Questions
Bar ChartComparing values across categories at a point in time or over timeWhich category is highest/lowest? By how much? Percentage change between years?
Line GraphTrends over time; multiple series comparisonMaximum/minimum value; steepest increase/decrease; when did X cross Y?
Pie ChartPart-to-whole relationships; proportionsWhat % does category X represent? How many more units than Y? What is the value if total = N?
TablePrecise numerical data; multiple variablesCalculate ratio, percentage, average from given numbers
Mixed DITwo types combined (table + pie chart); requires reading bothCombine data from both charts to answer; most complex type

DI Calculation Shortcuts

  • Percentage of total: (Part / Total) × 100 — memorise common fraction-percentage equivalents
  • Approximate calculations: round numbers for quick estimation; UPSC DI options are usually far apart enough to allow approximation
  • Growth rate: (New − Old) / Old × 100; for small growth rates, can approximate as (New − Old) / Old
  • Ratio comparison: cross-multiply to compare a/b vs c/d; no need to calculate actual values
  • Pie chart value: if sector angle = θ°, value = (θ/360) × Total; if percentage given directly, Value = (% / 100) × Total

Common DI Question Types and Approach

Question TypeQuick Approach
Percentage change (Year A to Year B)(B − A) / A × 100; if B > A → positive growth; if B < A → decline
Average of multiple yearsSum all values ÷ number of years; in bar/line chart, add up bars visually first
Ratio between two itemsRead values directly; reduce to simplest form; cross-multiply to compare
"By how much did X exceed Y?"Simple subtraction; read values for same year/category from chart
Percentage of total (pie chart)Read % directly OR (sector value / total) × 100
Maximum increase / steepest slopeScan all adjacent-year differences; pick largest; approximation usually sufficient

Time-Saving Tips for DI

  • Read the chart title, axis labels, and units FIRST before attempting questions
  • Do rough calculations — UPSC DI options are spread far enough that exact answers are rarely needed
  • For a set of 4–5 DI questions, spend no more than 6–7 minutes total
  • Skip calculation-heavy DI sets and return later if time permits
Key: DI = read chart axes and units first. Approximate to save time — UPSC options are far apart. Growth rate = (New − Old)/Old × 100. Pie chart value = (angle/360) × total. For ratios, cross-multiply instead of dividing. Spend ≤ 7 minutes per DI set.
6Decision Making & CSAT Strategy►

Decision making questions test your ability to choose the best course of action in a given situation. Combined with overall CSAT strategy, this chapter completes your preparation for the qualifying paper.

Decision Making Questions

  • A situation is described; you are asked to choose the best action from 4 options
  • These are not strictly logical questions — they test judgement, common sense, and awareness of administrative principles
  • Key principles for choosing the best answer:
    • Gather information before deciding (avoid knee-jerk reactions)
    • Follow established procedures and hierarchies
    • Minimise harm; protect public interest
    • Consult appropriate authorities when uncertain
    • Avoid extreme options (complete inaction or drastic unilateral action)
    • Ethical options generally score over merely legal ones
  • These questions are removed in recent years by UPSC from CSAT but may return; pattern-based, not formula-based

CSAT Exam Format Recap

ParameterDetail
Total questions80 MCQs
Total marks200 (2.5 marks each)
Duration2 hours (120 minutes)
Negative marking1/3rd of 2.5 = 0.833 marks per wrong answer
Qualifying marks33% = 66 out of 200
Counts for merit?No — qualifying only; does NOT add to GS Paper I score
LanguageBilingual (English + Hindi); choose either

Section-Wise Time Allocation (Recommended)

SectionApprox. QuestionsTimePriority
Reading Comprehension~2540–45 minHigh — most marks available
Data Interpretation~10–1215–20 minHigh — if strong in math
Logical Reasoning~15–1820–25 minMedium — speed practice needed
Basic Numeracy~10–1515–20 minMedium-Low — skip hard ones
Analytical Ability~8–1010–15 minMedium — arrangements can be time-consuming
Buffer / Review—5–10 minReview marked questions

Negative Marking Strategy

  • Negative marking = 1/3rd of marks per question (0.833 for CSAT, 0.66 for GS Paper I)
  • Attempt if you can eliminate at least 2 options (probability now 1/2 → positive expected value)
  • Skip if you have no idea — random guessing loses marks over time
  • Comprehension and logical reasoning questions are best for confident attempts; pure math is riskier if unsure

CSAT Preparation Tips

  • Don't ignore CSAT: many toppers have been eliminated by surprise CSAT difficulty spikes (2014 paper was notoriously hard)
  • Comprehension first: if you score 15+ in comprehension, you're already near the 33% threshold
  • Previous year papers: solve 7–8 past CSAT papers; patterns repeat; most effective preparation
  • Timed mock tests: practice under exam conditions (120 minutes, no breaks); builds stamina and time awareness
  • Weak area focus: identify your weakest section in mocks; improve it specifically; don't just practise what you're already good at
  • Calculator not allowed: practise mental maths; tables up to 20; squares up to 25; cubes up to 10
Key: CSAT = qualifying only; 33% = 66/200. 80 questions × 2.5 marks. Negative marking = 1/3rd (0.833). Attempt if you can eliminate 2 options. Comprehension = highest priority (25 questions). Solve 7–8 previous year CSAT papers — patterns repeat. Do not ignore CSAT.
★CSAT Paper II — Key Facts & Formulae►
TopicKey Fact / Formula
CSAT total marks200 (80 questions × 2.5 marks)
Qualifying marks33% = 66 marks; does NOT count for merit
Negative marking1/3 of 2.5 = 0.833 marks per wrong answer
Duration2 hours (120 minutes)
Comprehension questions~20–25 (from 4–5 passages); highest weightage
Comprehension ruleAnswer from passage only — not general knowledge
Syllogism ruleDraw ALL possible Venn diagrams; conclusion must hold in every diagram
Directions: morning shadowSun in East → shadow falls West
Directions: distanceNet displacement = √(a² + b²)
Percentage change formula(New − Old) / Old × 100
Successive % changesa + b + ab/100 (not simply a + b)
Average speedTotal Distance / Total Time (NOT average of speeds)
km/hr to m/sMultiply by 5/18
m/s to km/hrMultiply by 18/5
Simple InterestSI = PRT/100; A = P + SI
Compound InterestA = P(1 + R/100)ⁿ; CI – SI (2 yrs) = P(R/100)²
Work formula1-day work = 1/time; combined = 1/a + 1/b; time = ab/(a+b)
Downstream / UpstreamDownstream = B + R; Upstream = B − R
Pie chart formulaValue = (angle/360) × Total OR (% / 100) × Total
Alligation ruleMix ratio = (Higher − Mean) : (Mean − Lower)
Fractions to %1/4=25%, 1/3=33.3%, 1/6=16.7%, 1/8=12.5%, 3/4=75%
Assumption testRemove assumption → does statement collapse? If yes, it IS an assumption
Strong argumentDirectly relevant to central issue; practical; not emotional; not trivial
Negative marking thresholdAttempt if you can eliminate 2 of 4 options
Best preparationSolve 7–8 past CSAT papers under timed conditions