CSAT Paper II – Complete Study Notes for UPSC CSE Prelims

📊 CSAT Paper II 🔥 Day 1

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CSAT — Paper II — Complete Study Notes

6 chapters · UPSC CSE · Prelims Qualifying Paper

○ Not Started

CSAT (Civil Services Aptitude Test) is Paper II of the UPSC CSE Prelims — a qualifying-only paper covering reading comprehension, logical reasoning, analytical ability, basic numeracy, data interpretation, and decision making. Unlike GS Paper I, CSAT marks do not count toward merit — candidates only need 33% (66 out of 200) to qualify. But every year some well-prepared GS candidates are eliminated by a CSAT difficulty spike (2014 being the most notorious example), so it cannot be taken lightly. Every formula, worked example, diagram, and strategy note is included below.

Learning Objectives

After studying this chapter you will be able to:

Apply active reading strategies to answer comprehension questions strictly from the passage, avoiding common traps
Solve syllogisms using the Venn diagram method, and correctly resolve blood relation, coding-decoding, direction, and series problems
Distinguish assumptions from conclusions, and evaluate arguments as strong or weak using established tests
Apply percentage, ratio, profit-loss, time-speed-distance, interest, and work-time formulas with speed and accuracy
Read and calculate from bar charts, line graphs, pie charts, and tables using approximation techniques
Apply UPSC's negative marking rule strategically, attempting a question only when at least two options can be eliminated
Allocate exam time across sections based on question count and personal strength, maximising expected score within CSAT's 33% qualifying threshold

Exam Relevance

UPSC CSE★★★★★

State PSC★★★★☆

SSC CGL★★★☆☆

Banking★★★☆☆

💡 CSAT is qualifying-only (33% = 66/200) but is NOT to be ignored — comprehension (~25 questions) is your single highest-yield section. The same reasoning and numeracy skills also transfer directly to State PSC, SSC and Banking aptitude papers.

Concept Map

Reading Comprehension → Logical Reasoning

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Analytical Ability → Basic Numeracy

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Data Interpretation

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Decision Making & CSAT Strategy

Where This Fits

CSAT has no strict subject prerequisite — the reading, reasoning and numerical skills built here are foundational and also strengthen your approach to GS Paper I's data-heavy questions. Once you've worked through the chapters below, use the dynamic CSAT test generator on the CSAT hub page to build randomised practice sets by difficulty — or head to Study Material to explore other UPSC CSE subjects.

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1. Reading Comprehension

Question Types · Active Reading · Common Traps

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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.

1.1 CSAT Comprehension — Key Numbers

Aspect	Details
Typical passages	4–5 passages per paper; 200–400 words each; bilingual (English + Hindi)
Questions per passage	4–6 questions
Total comprehension questions	~20–25 (out of 80 total CSAT questions)
Passage topics	Social issues, environment, governance, science, philosophy, economics, history
Language of passage	Bilingual (English and Hindi provided); answer in any language you attempt

1.2 Types of Comprehension Questions

Question Type	How to Approach
Factual / Directly stated	Answer explicitly in passage; scan for keywords; do not infer beyond text
Inference / Implied meaning	Not stated but logically follows; must be grounded in passage; avoid over-inference
Central idea / Main theme	What is the passage primarily about? Eliminate options that are too narrow (one detail) or too broad
Author's tone / Attitude	How does the author feel about the subject? Critical / supportive / neutral / analytical / concerned
Title of passage	Best title = captures main theme; not too narrow or specific; not too broad
Vocabulary in context	What does the underlined word mean in THIS context? Choose the 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

1.3 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 the passage
Time allocation: spend 6–8 minutes per passage (read + answer); do not exceed 10 minutes on a single passage

1.4 Common Traps in Comprehension

Too extreme: options using "always", "never", "only", "all" are usually wrong unless the 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: the correct answer is often a paraphrase of the passage, not a word-for-word copy; do not reject paraphrased options

💡 Read questions BEFORE the passage. Answer strictly from the passage — never from general knowledge. Comprehension = ~25 questions, the highest time investment and highest-scoring section. Tone questions: look for emotional/attitudinal language in the passage. "NOT correct" questions: verify each statement individually.

Question Volume

~20–25 of 80 questions from 4–5 passages

Time Budget

6–8 min/passage; never exceed 10 min

Core Rule

Answer from passage only — not general knowledge

Example 1 — Central Idea vs Detail

Given: A passage discusses how urban flooding results from encroachment on wetlands, poor drainage design, and unregulated construction, using one city's 2019 flood as a case study. Which option best captures the passage's main theme — "The 2019 flood in the city was severe" or "Unplanned urbanisation increases flood vulnerability"?

Solution: The first option is just one supporting detail (too narrow); the second captures the passage's overall argument, of which the flood example is illustrative.

Answer: "Unplanned urbanisation increases flood vulnerability" — the central idea, not a narrow detail.

Example 2 — Inference vs Outside Knowledge

Given: A passage states "The policy was implemented in 2015 and led to a 12% rise in enrolment by 2018." An option claims "The policy was universally successful across all regions." Is this a valid inference?

Solution: The passage only supports a national/aggregate rise; it says nothing about uniform success across every region — that claim goes beyond what is stated or logically implied.

Answer: Not a valid inference — reject it as an over-extension beyond the passage (an "outside knowledge" / over-inference trap).

Example 3 — Author's Tone

Given: A passage repeatedly uses phrases like "regrettably", "falls short of", and "a missed opportunity" when describing a government scheme. What is the author's tone?

Solution: These phrases carry a consistently negative/evaluative charge about the scheme's performance, without being purely factual or celebratory.

Answer: Critical / disappointed tone — identified by scanning for emotionally loaded language, exactly as the active-reading strategy recommends.

Fig. 1.1 — Active reading strategy: skim the questions, read the passage actively, identify its structure, then answer strictly from the passage.

Q1. For "According to the passage" questions, you should answer based on:

CSAT comprehension tests reading ability, not subject knowledge — the correct answer must always be traceable to the passage itself.

Q2. An option containing words like "always", "never", or "only" is usually:

Extreme-language options overreach beyond typical passage support and are a classic CSAT trap unless the passage itself makes an equally absolute claim.

Q3. The recommended first step before reading a CSAT comprehension passage is to:

Skimming the questions first focuses your active reading — you know exactly what details, tone, or inference the questions will ask about.

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2. Logical Reasoning

Syllogisms · Blood Relations · Coding-Decoding · Directions · Series

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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.

2.1 Syllogisms

Two or more statements (premises) → conclusion; test if the 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

2.2 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

2.3 Coding-Decoding

Type	Approach
Letter shifting	Find the shift pattern (+2, −3, etc.); apply consistently; check if same shift for all letters
Position reversal	DELHI → IHLED; check if word is reversed
Number-letter coding	A=1, B=2 ... Z=26; or A=26, B=25 (reverse); identify the pattern
Symbol coding	Each letter replaced by a symbol; find pattern from given example
Conditional coding	Rules given (e.g., vowels coded differently from consonants); apply each rule

2.4 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 the Pythagoras theorem for net displacement \((a^2 + b^2 = c^2)\)

2.5 Series Completion

Number series: find the rule (arithmetic progression, geometric progression, squares, cubes, differences of differences)
Letter series: find the 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 the difference between consecutive terms; if not constant, find second-order differences

💡 Syllogisms → always use Venn diagrams; check ALL valid diagrams. Blood relations → draw the family tree first. Directions → draw a compass; use Pythagoras for distance. Series → find differences first, then second-order differences if needed. Coding → look for a consistent shift pattern.

Net Displacement (Directions)

\( \text{Distance} = \sqrt{a^2+b^2} \) (Pythagoras)

Letter-Number Coding

A=1…Z=26 (forward) or A=26…Z=1 (reverse)

Syllogism Validity Test

Conclusion must hold in ALL possible Venn diagrams

Example 1 — Syllogism with Venn Diagrams

Given: Statements: "All cats are animals." "Some animals are wild." Conclusion: "Some cats are wild." Is this valid?

Solution: Draw the Venn diagrams: cats fully inside animals; "some animals are wild" overlaps animals with a wild circle, but that overlap need not touch the cats circle at all — it's possible for wild animals to be entirely non-cats.

Answer: Not valid — the conclusion does not hold in every possible diagram, since the "wild" overlap can avoid the cats region entirely.

Example 2 — Directions and Distance

Given: A man walks 8 km East, then 6 km North. Find his straight-line distance from the starting point.

Solution: This forms a right triangle with legs 8 km and 6 km.

\( \text{Distance} = \sqrt{8^2+6^2} = \sqrt{64+36} = \sqrt{100} = 10 \) km

Answer: 10 km from the starting point.

Example 3 — Letter Series

Given: Find the next term: B, D, G, K, P, ?

Solution: Differences in position: B(2)→D(4): +2; D(4)→G(7): +3; G(7)→K(11): +4; K(11)→P(16): +5. The differences themselves increase by 1 each time (second-order pattern), so the next gap is +6.

Answer: P(16)+6 = position 22 = V

Fig. 2.1 — The three standard syllogism forms drawn as Venn diagrams: All A are B (A fully inside B), Some A are B (partial overlap), No A is B (fully separate).

Q1. In syllogisms, a conclusion is valid only if it holds true in:

A syllogism conclusion is only valid if it necessarily follows — meaning it must hold in every diagram consistent with the given premises, not just some.

Q2. If both given premises are negative (e.g., "No A is B", "No B is C"), the correct conclusion is:

Two negative premises never yield a definite conclusion — this is one of the standard syllogism rules to memorise.

Q3. If the sun rises in the East, a person's morning shadow falls toward the:

A shadow always falls on the side opposite the light source — since the morning sun is in the East, the shadow falls toward the West.

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3. Analytical Ability

Arrangements · Assumption · Conclusion · Argument · Cause-Effect

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

3.1 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

3.2 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"
An 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)

3.3 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)

3.4 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?"

3.5 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

💡 Arrangements → draw and fill step by step. Assumption = unstated necessity; test by removing it. Conclusion = what logically follows; must not go beyond the statements. Strong argument = directly relevant, practical, substantial. Cause-effect → identify temporal sequence and mechanism.

Assumption Test

Remove it → does the statement collapse? If yes, it IS an assumption

Conclusion Test

Must follow from ALL statements; must not contradict or over-extend

Strong Argument Test

Directly relevant + practical + substantial to the central issue

Example 1 — Circular Arrangement

Given: Six people A, B, C, D, E, F sit around a circular table facing the centre. A sits immediately to the right of B. C sits opposite A. Find C's position relative to B.

Solution: Fix B as the reference (0°). A is immediately right of B (adjacent, clockwise). "Opposite A" means directly across the table from A (3 seats away in a hexagon).

Answer: C sits three seats away from A (diametrically opposite), which places C two seats clockwise from B's own opposite position — solved by fixing one person and filling the rest relative to them.

Example 2 — Statement-Assumption

Given: Statement: "Please switch off the lights when leaving the room to save electricity." Assumption: "Switching off lights when not in use saves electricity."

Solution: Test: without this assumption, would the instruction make sense? No — the entire instruction depends on the (unstated but obvious) fact that turning off unused lights saves electricity.

Answer: The assumption is implicit and necessary — it IS a valid assumption.

Example 3 — Strong vs Weak Argument

Given: Statement: "Should all new government buildings be required to install solar panels?" Argument I: "Yes, it reduces long-term electricity costs and supports national renewable energy targets." Argument II: "No, solar panels look ugly on colonial-style buildings."

Solution: Argument I is directly relevant, practical, and addresses cost/policy substance. Argument II is trivial/aesthetic and does not address the core cost-benefit or policy question.

Answer: Argument I is strong; Argument II is weak (trivial, not substantial to the central issue).

Fig. 3.1 — Circular arrangement strategy: fix one person (B) as the reference point, then place all others clockwise/anticlockwise using the given relative clues.

Q1. An "assumption" in Statement-Assumption questions is best defined as:

An assumption is an unstated but necessary premise — if explicitly stated, it would not be "implicit" and would not qualify as an assumption.

Q2. A "strong" argument in Statement-Argument questions is one that is:

Strong arguments directly address the core issue with practical, substantial reasoning — not emotion, triviality, or hypotheticals.

Q3. In circular arrangement puzzles, the standard first step is to:

Since only relative positions matter in circular arrangements, fixing one person as a reference point lets you place everyone else correctly and consistently.

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4. Basic Numeracy

Percentages · Ratios · Profit-Loss · TSD · Interest · Averages · Work-Time

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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.

4.1 Percentages

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 \(\dfrac{r}{100+r} \times 100\%\) to keep expenditure constant

4.2 Ratios and Proportions

Mixture problems: use alligation to find the ratio of mixing two quantities
Alligation: \(|\text{Higher price} - \text{Mean price}| : |\text{Mean price} - \text{Lower price}| = \text{parts of lower} : \text{parts of higher}\)

4.3 Profit and Loss, Time-Speed-Distance

Profit/Loss percentages are always calculated on Cost Price (CP), never on Selling Price (SP)
Average speed uses total distance and total time — NOT the arithmetic average of the individual speeds
Relative speed: same direction subtracts the two speeds; opposite direction adds them
Convert km/hr to m/s: multiply by \(\dfrac{5}{18}\) | m/s to km/hr: multiply by \(\dfrac{18}{5}\)

4.4 Simple/Compound Interest, Averages, Work and Time

CI − SI (for 2 years) always equals \(P \times (R/100)^2\) — a frequently tested shortcut
Weighted average accounts for different quantities/weights, not a simple arithmetic mean
Efficiency ratio is the inverse of the time ratio — the faster worker has the higher efficiency
Pipes: a filling pipe contributes a positive rate; an emptying pipe contributes a negative rate; net rate is the sum

💡 Average speed = total distance ÷ total time (NOT the 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.

Percentages

\(x\% \text{ of } y = \dfrac{x \times y}{100}\)

\(\%\,change = \dfrac{Change}{Original} \times 100\)

Successive: \(a+b+ab/100\)

x% more/less than

More: \(A = B(1+x/100)\)

Less: \(A = B(1-x/100)\)

Ratios & Alligation

\(\text{If } a{:}b=m{:}n,\ a=km,\ b=kn\)

Componendo: \(\dfrac{a+b}{a-b}=\dfrac{m+n}{m-n}\)

Profit and Loss

\(Profit\% = \dfrac{Profit}{CP}\times100\)

\(SP = \dfrac{CP(100+P\%)}{100}\)

False weight: \(Profit\% = \dfrac{e}{W-e}\times100\)

Time, Speed, Distance

\(D = S\times T\); \(\text{Avg speed}=\dfrac{\text{Total dist.}}{\text{Total time}}\)

Relative: same dir. \(=S_1-S_2\); opp. \(=S_1+S_2\)

Boats: up \(=B-R\); down \(=B+R\)

Simple & Compound Interest

\(SI=\dfrac{PRT}{100}\); \(A=P(1+R/100)^n\)

\(CI-SI\ (2\text{yr})=P(R/100)^2\)

Averages

\(Average=\dfrac{\text{Sum}}{\text{Count}}\)

\(\text{Weighted avg}=\dfrac{\sum w_ix_i}{\sum w_i}\)

Work and Time

1-day work \(=1/a\); combined \(=1/a+1/b\)

\(time=ab/(a+b)\)

Example 1 — Successive Percentage Change

Given: A shopkeeper marks up an item's price by 25%, then gives a discount of 20% on the marked-up price. Find the net percentage change.

Solution: Using successive change formula with \(a=25,\ b=-20\):

\( \text{Net} = 25 + (-20) + \dfrac{25\times(-20)}{100} = 5 - 5 = 0\% \)

Answer: 0% — the price is unchanged after the markup and discount cancel out exactly.

Example 2 — Train Crossing a Pole

Given: A train 150 m long crosses a pole in 10 seconds. Find its speed in km/hr.

Solution: Crossing a pole means covering a distance equal to the train's own length.

\( Speed = \dfrac{150}{10} = 15\ \text{m/s} = 15\times\dfrac{18}{5} = 54\ \text{km/hr} \)

Answer: 54 km/hr.

Example 3 — Work and Time

Given: A can complete a job in 12 days, B in 18 days. In how many days will they finish it working together?

Solution:

\( time = \dfrac{ab}{a+b} = \dfrac{12\times18}{12+18} = \dfrac{216}{30} = 7.2 \) days

Answer: 7.2 days (7 days and 4.8 hours) working together.

Fig. 4.1 — Alligation cross method: the mixing ratio of the lower-priced to higher-priced quantity equals (Higher − Mean) : (Mean − Lower).

Q1. Average speed for a journey is calculated as:

Average speed must account for the actual time spent at each speed, so it is total distance divided by total time — not a simple average of the speed values.

Q2. If a price increases by r%, by what percentage must the quantity consumed decrease to keep total expenditure unchanged?

To keep expenditure (price × quantity) constant when price rises by r%, quantity must fall by r/(100+r) × 100%, not simply by r%.

Q3. CI − SI for a 2-year period is given by:

The difference between compound and simple interest over 2 years arises purely from interest-on-interest in the second year, which simplifies to P(R/100)².

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5. Data Interpretation

Chart Types · Calculation Shortcuts · Time-Saving Approach

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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.

5.1 Types of DI Charts

Chart Type	Best For	Common Questions
Bar Chart	Comparing values across categories at a point in time or over time	Which category is highest/lowest? By how much? Percentage change between years?
Line Graph	Trends over time; multiple series comparison	Maximum/minimum value; steepest increase/decrease; when did X cross Y?
Pie Chart	Part-to-whole relationships; proportions	What % does category X represent? How many more units than Y? What is the value if total = N?
Table	Precise numerical data; multiple variables	Calculate ratio, percentage, average from given numbers
Mixed DI	Two types combined (table + pie chart); requires reading both	Combine data from both charts to answer; most complex type

5.2 DI Calculation Shortcuts

Percentage of total: \(\dfrac{\text{Part}}{\text{Total}} \times 100\) — 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: \(\dfrac{\text{New} - \text{Old}}{\text{Old}} \times 100\); for small growth rates, can approximate as \(\dfrac{\text{New} - \text{Old}}{\text{Old}}\)
Ratio comparison: cross-multiply to compare \(a/b\) vs \(c/d\); no need to calculate actual values
Pie chart value: if the sector angle \(=\theta^{\circ}\), \(value = \dfrac{\theta}{360} \times Total\); if percentage given directly, \(Value = \dfrac{\%}{100} \times Total\)

5.3 Common DI Question Types and Approach

Question Type	Quick Approach
Percentage change (Year A to Year B)	\(\dfrac{B - A}{A} \times 100\); if B > A → positive growth; if B < A → decline
Average of multiple years	Sum all values ÷ number of years; in bar/line charts, add up the bars visually first
Ratio between two items	Read values directly; reduce to simplest form; cross-multiply to compare
"By how much did X exceed Y?"	Simple subtraction; read values for the same year/category from the chart
Percentage of total (pie chart)	Read % directly OR \(\dfrac{\text{sector value}}{\text{total}} \times 100\)
Maximum increase / steepest slope	Scan all adjacent-year differences; pick the largest; approximation is usually sufficient

5.4 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 apart 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

💡 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.

Percentage of Total

\( \dfrac{\text{Part}}{\text{Total}}\times100 \)

Growth Rate

\( \dfrac{\text{New}-\text{Old}}{\text{Old}}\times100 \)

Pie Chart Value

\( Value=\dfrac{\theta}{360}\times Total \)

or \( \dfrac{\%}{100}\times Total \)

Ratio Comparison

\( \dfrac{a}{b} \) vs \( \dfrac{c}{d} \): compare \(ad\) vs \(cb\)

Example 1 — Pie Chart Value from Angle

Given: In a pie chart, the sector representing "Education" spending has a central angle of 72°. Total spending = ₹5,00,000. Find the amount spent on Education.

Solution:

\( Value = \dfrac{72}{360}\times 5{,}00{,}000 = 0.2\times5{,}00{,}000 = 1{,}00{,}000 \)

Answer: ₹1,00,000 spent on Education.

Example 2 — Growth Rate

Given: A city's population grew from 8 lakh in 2015 to 10 lakh in 2020. Find the percentage growth.

Solution:

\( \text{Growth} = \dfrac{10-8}{8}\times100 = \dfrac{2}{8}\times100 = 25\% \)

Answer: 25% growth over the period.

Example 3 — Ratio Comparison by Cross-Multiplication

Given: Which is larger, \(7/12\) or \(5/9\)?

Solution: Cross-multiply: \(7\times9=63\); \(5\times12=60\). Since \(63>60\), the first fraction is larger.

Answer: \(7/12 > 5/9\) — solved instantly without converting to decimals.

Fig. 5.1 — Two common DI chart types: bar charts for comparing values across categories, and pie charts for part-to-whole proportions.

Q1. A pie chart sector has a central angle of 90°. If the total = 800, the value represented is:

Value = (angle/360) × Total = (90/360) × 800 = 0.25 × 800 = 200.

Q2. To compare two ratios a/b and c/d quickly without computing decimals, the best approach is:

Cross-multiplication instantly compares two fractions without needing to compute decimal values — a major time-saver in DI.

Q3. The growth rate from an Old value to a New value is calculated as:

Growth rate is the change expressed as a percentage of the original (Old) value, not the raw difference or an inverted ratio.

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6. Decision Making & CSAT Strategy

Decision Making Questions · Exam Format · Time Allocation · Negative Marking

○ Not Started

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.

6.1 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 were removed in recent years by UPSC from CSAT but may return; they are pattern-based, not formula-based

6.2 CSAT Exam Format Recap

Parameter	Detail
Total questions	80 MCQs
Total marks	200 (2.5 marks each)
Duration	2 hours (120 minutes)
Negative marking	1/3rd of 2.5 = 0.833 marks per wrong answer
Qualifying marks	33% = 66 out of 200
Counts for merit?	No — qualifying only; does NOT add to GS Paper I score
Language	Bilingual (English + Hindi); choose either

6.3 Section-Wise Time Allocation (Recommended)

Section	Approx. Questions	Time	Priority
Reading Comprehension	~25	40–45 min	High — most marks available
Data Interpretation	~10–12	15–20 min	High — if strong in math
Logical Reasoning	~15–18	20–25 min	Medium — speed practice needed
Basic Numeracy	~10–15	15–20 min	Medium-Low — skip hard ones
Analytical Ability	~8–10	10–15 min	Medium — arrangements can be time-consuming
Buffer / Review	—	5–10 min	Review marked questions

6.4 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

6.5 CSAT Preparation Tips

Don't ignore CSAT: many toppers have been eliminated by surprise CSAT difficulty spikes (the 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: practise 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

💡 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.

Total Marks

80 questions × 2.5 marks = 200 marks

Negative Marking

1/3 × 2.5 = 0.833 marks deducted per wrong answer

Qualifying Threshold

33% = 66/200 marks (does not count for merit)

Attempt Rule

Attempt only if ≥2 of 4 options can be eliminated

Example 1 — Expected Value of Attempting a Question

Given: You can eliminate 2 of 4 options in a question. Each correct answer is worth +2.5 marks; a wrong answer costs −0.833 marks. Should you attempt it?

Solution: With 2 options eliminated, probability of being correct = 1/2.

\( EV = 0.5\times2.5 + 0.5\times(-0.833) = 1.25 - 0.4165 = 0.8335 \)

Answer: Expected value is positive (+0.8335 marks) — attempt the question.

Example 2 — Marks Needed to Qualify

Given: A candidate attempts 60 of 80 questions and gets 45 correct, 15 wrong. Does the candidate qualify?

Solution:

\( \text{Score} = 45\times2.5 - 15\times0.833 = 112.5 - 12.5 = 100 \) marks

Answer: 100 marks out of 200 (50%) — comfortably above the 33% (66-mark) qualifying threshold.

Example 3 — Time Allocation Check

Given: Using the recommended time allocation, a candidate spends 45 min on Comprehension, 20 min on DI, 22 min on Logical Reasoning, 18 min on Numeracy, and 12 min on Analytical Ability. How much buffer time remains in the 120-minute paper?

Solution:

\( \text{Used} = 45+20+22+18+12 = 117 \) min

Answer: \(120-117=3\) minutes of buffer — tight, confirming why sticking closely to the recommended allocation matters.

Fig. 6.1 — Recommended time allocation across the 120-minute CSAT paper: Reading Comprehension gets the largest share since it carries the most questions and highest scoring potential.

Q1. Under CSAT's negative marking scheme, you should attempt a question only if you can eliminate:

Eliminating 2 of 4 options raises the probability of a correct guess to 1/2, which makes the expected value of attempting positive despite the negative marking penalty.

Q2. CSAT Paper II marks count toward:

CSAT is a qualifying-only paper — candidates must score at least 33% (66/200) but the score itself is not added to the GS Paper I merit ranking.

Q3. Given typical question counts, the single highest-priority section to master for CSAT is:

With ~20–25 of the 80 total questions, Reading Comprehension carries the most marks and is the highest-priority section for strategic time investment.

📚

7. Quick Revision

Key Facts & Formulae · Exam-Angle Summary · Practice

○ Not Started

A. Key Facts & Formulae at a Glance

CSAT Total Marks

200 (80 questions × 2.5 marks)

Qualifying Marks

33% = 66 marks; does NOT count for merit

Negative Marking

1/3 of 2.5 = 0.833 marks per wrong answer

Duration

2 hours (120 minutes)

Comprehension Questions

~20–25 (from 4–5 passages); highest weightage

Syllogism Rule

Draw ALL possible Venn diagrams; conclusion must hold in every one

Directions: Distance

\( \text{Net displacement} = \sqrt{a^2 + b^2} \)

Percentage Change

\( \dfrac{\text{New} - \text{Old}}{\text{Old}} \times 100 \)

Successive % Changes

\( a + b + ab/100 \) (not simply a + b)

Average Speed

\( \dfrac{\text{Total Distance}}{\text{Total Time}} \) (NOT average of speeds)

km/hr ↔ m/s

×5/18 (to m/s); ×18/5 (to km/hr)

Simple & Compound Interest

\( SI=\dfrac{PRT}{100} \); \( A=P(1+R/100)^n \)

CI − SI (2 years)

\( P(R/100)^2 \)

Work Formula

1-day work \(=1/time\); combined \(=1/a+1/b\); \(time=ab/(a+b)\)

Downstream / Upstream

\( Downstream=B+R \); \( Upstream=B-R \)

Pie Chart Formula

\( \dfrac{angle}{360}\times Total \) OR \( \dfrac{\%}{100}\times Total \)

Alligation Rule

Mix ratio \(=(\text{Higher}-\text{Mean}):(\text{Mean}-\text{Lower})\)

Assumption Test

Remove it — does the statement collapse? If yes, it IS an assumption

Negative Marking Threshold

Attempt if you can eliminate 2 of 4 options

B. Exam-Angle Summary

Topic	UPSC CSE Focus	State PSC Focus	SSC / Banking Focus
Reading Comprehension	Bilingual passages; inference and tone questions common	Similar passage-based comprehension, often shorter	Vocabulary-in-context and factual questions dominate
Logical Reasoning	Syllogism, directions, series — moderate difficulty	Similar topics; blood relations frequently tested	Heavier coding-decoding and series emphasis
Analytical Ability	Statement-assumption/conclusion; circular arrangements	Linear/circular arrangements common	Puzzle-heavy; floor/building arrangements frequent
Basic Numeracy	Application-based; moderate calculation load	Similar formulae; state-specific numericals rare	Heavier calculation load; speed is critical
Data Interpretation	Table + pie chart mixed DI; approximation-friendly	Bar/line chart heavy	Table-based DI with precise calculation demands
Decision Making & Strategy	Rare now, but negative-marking strategy always relevant	Similar qualifying-paper strategy applies	No decision-making section; strategy still applies to overall attempt planning

C. Mnemonics & Memory Aids

💡 "Questions First, Passage Second": always skim the questions before reading a comprehension passage, so you read with purpose.

💡 "All Diagrams Must Agree": a syllogism conclusion is valid only if it holds in every possible Venn diagram, not just one.

💡 "Assumption In, Conclusion Out": an assumption is an unstated INPUT the argument relies on; a conclusion is the logically derived OUTPUT.

💡 "Distance, not Time, Averages Speed": average speed = total distance ÷ total time — never average the individual speeds directly.

💡 "Two to Attempt": under CSAT's negative marking, only attempt a question if you can eliminate at least 2 of the 4 options.

💡 "33 to Survive": CSAT's qualifying threshold is 33% (66/200) — it does not add to your GS Paper I merit score.

Practice Questions

Q1. A shopkeeper marks up an item by 25% and then gives a discount of 20%. Find the net percentage change in price.

Show Answer

\( \text{Net} = 25+(-20)+\dfrac{25\times(-20)}{100} = 5-5 = 0\% \) — price unchanged

Q2. A train 150 m long crosses a pole in 10 seconds. Find its speed in km/hr.

Show Answer

\( Speed = 150/10 = 15\ \text{m/s} = 15\times18/5 = 54\ \text{km/hr} \)

Q3. In a pie chart, a sector representing "Education" has a central angle of 72°. If total spending = ₹5,00,000, find the amount spent on Education.

Show Answer

\( Value = (72/360)\times5{,}00{,}000 = 1{,}00{,}000 \) — ₹1,00,000

Q4. A man walks 5 km East, then 12 km North. Find his straight-line distance from the starting point.

Show Answer

\( \text{Distance} = \sqrt{5^2+12^2} = \sqrt{25+144} = \sqrt{169} = 13\ \text{km} \)

Q5. If you can eliminate 2 of 4 options (50% chance of being correct, +2.5 marks if right, −0.833 if wrong), find the expected value of attempting.

Show Answer

\( EV = 0.5\times2.5 + 0.5\times(-0.833) = 1.25-0.4165 = 0.8335 \) — positive, so attempt the question

Mini Quiz — Full Chapter Recap

Q1. CSAT's qualifying threshold is:

CSAT requires only 33% (66 out of 200 marks) to qualify — it is a qualifying paper, not counted toward merit.

Q2. The negative marking penalty per wrong answer in CSAT is:

CSAT deducts 1/3rd of a question's marks for a wrong answer — 1/3 × 2.5 = 0.833 marks.

Q3. The single most effective preparation strategy repeatedly recommended for CSAT is:

Solving previous years' papers under timed, exam-like conditions is the most effective preparation because CSAT question patterns repeat closely year to year.

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Learning Objectives

Exam Relevance

Concept Map

Where This Fits

1.1 CSAT Comprehension — Key Numbers

1.2 Types of Comprehension Questions

1.3 Active Reading Strategy

1.4 Common Traps in Comprehension

Question Volume

Time Budget

Core Rule

Example 1 — Central Idea vs Detail

Example 2 — Inference vs Outside Knowledge

Example 3 — Author's Tone

2.1 Syllogisms

2.2 Blood Relations

2.3 Coding-Decoding

2.4 Directions

2.5 Series Completion

Net Displacement (Directions)

Letter-Number Coding

Syllogism Validity Test

Example 1 — Syllogism with Venn Diagrams

Example 2 — Directions and Distance

Example 3 — Letter Series

3.1 Arrangement Problems

3.2 Statement — Assumption

3.3 Statement — Conclusion

3.4 Statement — Argument (Strong vs Weak)

3.5 Cause and Effect

Assumption Test

Conclusion Test

Strong Argument Test

Example 1 — Circular Arrangement

Example 2 — Statement-Assumption

Example 3 — Strong vs Weak Argument

4.1 Percentages

4.2 Ratios and Proportions

4.3 Profit and Loss, Time-Speed-Distance

4.4 Simple/Compound Interest, Averages, Work and Time

Percentages

x% more/less than

Ratios & Alligation

Profit and Loss

Time, Speed, Distance

Simple & Compound Interest

Averages

Work and Time

Example 1 — Successive Percentage Change

Example 2 — Train Crossing a Pole

Example 3 — Work and Time

5.1 Types of DI Charts

5.2 DI Calculation Shortcuts

5.3 Common DI Question Types and Approach

5.4 Time-Saving Tips for DI

Percentage of Total

Growth Rate

Pie Chart Value

Ratio Comparison

Example 1 — Pie Chart Value from Angle

Example 2 — Growth Rate

Example 3 — Ratio Comparison by Cross-Multiplication

6.1 Decision Making Questions

6.2 CSAT Exam Format Recap

6.3 Section-Wise Time Allocation (Recommended)

6.4 Negative Marking Strategy

6.5 CSAT Preparation Tips

Total Marks

Negative Marking

Qualifying Threshold

Attempt Rule

Example 1 — Expected Value of Attempting a Question

Example 2 — Marks Needed to Qualify

Example 3 — Time Allocation Check

A. Key Facts & Formulae at a Glance

CSAT Total Marks

Qualifying Marks

Negative Marking

Duration