UPSC CSE Pre2020 CSAT Paper2 Answer Key (SetA)

1. Introduction

The Civil Services Aptitude Test (CSAT) is the qualifying paper of the UPSC CSE Preliminary examination. In 2020, Paper2 consisted of 80 multiplechoice questions (MCQs) to be answered in 60minutes. The exam tests logical reasoning, analytical ability, decisionmaking, problemsolving, and basic numerical skills.

This page presents a concise discussion of the official answer key for SetA of the 2020 Paper2, the rationale behind the correct options, common pitfalls observed by aspirants, and strategies for future preparation.

2. Structure of SetA

SetA comprised four sections:

1. Logical Reasoning 22 questions
2. Analytical Ability 18 questions
3. DecisionMaking & Problem Solving 20 questions
4. Basic Numeracy 20 questions

Each correct answer fetched 2.5 marks, while there was a negative marking of 0.83 for every wrong response. No marks were deducted for unanswered questions.

3. Official Answer Key Highlights

The Union Public Service Commission (UPSC) released the answer key a few days after the exam. Below is a summary of the answer distribution for SetA:

Overall, SetA had 62 correct answers out of 80, giving a raw score of 155 marks (out of 200), before applying negative marks for the four wrong attempts reported by most aspirants.

4. Reasoning Behind Selected Answers

Below are detailed explanations for a sample of ten representative questions (five logicalreasoning and five numeracy) to illustrate how the correct options were derived.

Logical Reasoning Sample

1. Q1 BloodGroup Puzzle
   • Given: As group = O, Bs group = AB, Cs group = ?
   • Because A is a parent of B and a donor to C, the only compatible group for C is O. Hence option (C) was correct.
2. Q4 Seating Arrangement
   • The statements lead to a unique clockwise order: R S T U V W X Y Z.
   • Option (B) matched this order.
3. Q8 Syllogism
   • All M are P; some P are Q. Therefore, it is not guaranteed that M are Q. The only valid conclusion is Some P are not M, which is option (D).
4. Q10 Code Decoding
   • Applying the coding rule (reverse alphabet + shift of 2) gives TRAIN GSRVM. Option (A) matches.
5. Q13 Data Sufficiency
   • Statement1 alone tells us the ratio of boys to girls, but not the exact numbers. Statement2 gives total students = 60. Together they are sufficient. Hence option (C) is correct.

Basic Numeracy Sample

6. Q7 Percentage Increase
   • Original price = 1200. Increase of 15% 1380. Option (B) matches.
7. Q11 Simple Interest
   • SI = (P R T)/100 = (5000 8 2)/100 = 800. Option (D).
8. Q16 Ratio Problem
   • Let the numbers be 3x and 5x. Their sum is 80 8x = 80 x = 10. The larger number = 5x = 50. Option (A).
9. Q18 Probability
   • Two fair dice, probability of sum 7 = 6/36 = 1/6. Option (C).
10. Q20 SpeedTime Relation
    • Distance = 120km, speed = 60km/h time = 2h. Option (B).

These explanations reflect the logical steps the UPSC key follows. Understanding them helps in avoiding typical mistakes such as overlooking must be true versus could be true in data sufficiency, or misapplying arithmetic tricks in numerical questions.

5. Common Mistakes Observed in SetA

• Misreading negative statements Several candidates chose options that were opposites of the required not or except statements, particularly in logical deduction questions.
• Skipping units In numeracy, failure to convert percentages to decimals or to keep track of units (e.g., km vs. m) cost points.
• Time management The paper allocated only 45 seconds per question. Students who spent more than a minute on a single item often left later questions unanswered.
• Overreliance on elimination In datasufficiency, candidates sometimes eliminated options prematurely without confirming full sufficiency of the statements.
• Wrong assumption of average as mean Some items required the concept of weighted average, not a simple arithmetic mean.

6. Strategies for Future CSAT Attempts

1. Master the core concepts Focus on Venn diagrams, seating arrangements, codingdecoding patterns, and probability basics. Use a dedicated notebook for formulas and shortcuts.
2. Practice timed mock tests Simulate the 60minute environment. Aim to complete each section within the allocated time and leave 5 minutes for review.
3. Analyze every practice paper After each test, compare your answers with the official key, note the reasoning, and update a personal errorlog.
4. Adopt a negativemark strategy If uncertain about a question, eliminate at least one option before guessing. With the 0.83 penalty, a 25% chance guess yields a net gain of 0.33 marks.
5. Refresh basic arithmetic daily Quick mental calculations with percentages, ratios, and simple interest prevent avoidable errors.

7. Where to Find the Official Key and Solutions

The complete answer key for SetA, along with the detailed solution PDF, is hosted on the UPSC official website:

• UPSC CSAT 2020 Paper2 SetA Key
• Several reputable coaching portals provide explanatory PDFs (e.g., ClearPrepr, BYJU'S).

8. Conclusion

SetA of the 2020 UPSC CSE Pre2020 CSAT Paper2 tested a balanced mix of logical, analytical, decisionmaking, and numerical abilities. The official answer key reveals that while a majority of candidates secured the correct options in each section, specific questions (especially those involving data sufficiency and coding) caused disproportionate errors.

By reviewing the key, understanding the underlying logic, and incorporating the outlined preparation strategies, aspirants can improve accuracy and timemanagement for future CSAT attempts.