2026 CSAT, all questions

UPSC Prelims 2026 · CSAT

Question 1: Data Interpretation

X receives three coins of different denominations : 1, 2, 5, 10 and 20. If the total amount received by X is m, does X receive a coin of denomination 5?

  1. Statement Im is not a prime number.
  2. Statement IIThe sum of the digits of m is greater than 5.

Each item in this section contains a question followed by two statements. Answer each item using the following instructions and mark your response on the Answer Sheet accordingly.

aSelect this option if the question can be answered using one of these statements alone, but cannot be answered using other statement
bSelect this option if the question can be answered using either statement alone
cSelect this option if the question can be answered using both the statements together, but cannot be answered using either statement alone
dSelect this option if the question cannot be answered even using any of the statements

AnswerUPSC’s answer is (a).

Three different coins from 1, 2, 5, 10, 20 give ten possible totals. Sets with a 5 total 8, 16, 26, 17, 27 or 35, and every digit sum there exceeds 5. Sets without a 5 total 13, 23, 31 or 32, and every digit sum there is 4 or 5. So Statement II alone settles it: X does receive a 5. Statement I fails because 8 and 32 are both non-prime, yet only 8 comes from a set with a 5.

Why each option is right or wrong
  • (a) Right: II alone decides it, while I alone does not (total 8 has a 5, total 32 does not).
  • (b) Wrong: I alone is not enough, since the non-prime totals 8 and 32 give opposite answers.
  • (c) Wrong: II alone is already sufficient, so the two do not need to be combined.
  • (d) Wrong: Statement II by itself answers the question.

Only the provisional key (27 May 2026) was found; the final key replaces it when found.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2026, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.