UPSC Prelims 2026 · CSAT
Question 8: Basic Numeracy
The weight of X, in kg, is denoted by X. The weights of A, B, C, D, P, Q, R and S are measured. Given :
| A + B + C + D = 17 |
| A + C = 6 |
| P + Q + S + D = 15 |
| P + Q + R + B = 17 |
| P = R and Q = S |
Which one of the following statements is correct?
AnswerUPSC’s answer is (b).
From the first two equations, B + D = 17 − 6 = 11. Using P = R and Q = S, the other two become P + 2Q + D = 15 and 2P + Q + B = 17. Adding them gives 3(P + Q) + (B + D) = 32, so 3(P + Q) = 21 and P + Q = 7 kg. A + C is 6 kg, so P and Q together weigh more than A and C. The data cannot separate P from Q, and B + D = 11 exceeds 7.
Why each option is right or wrong
- (a) Wrong: B + D = 11 kg, which is more than P + Q = 7 kg.
- (b) Right: P + Q = 7 kg exceeds A + C = 6 kg.
- (c) Wrong: the equations never fix P against Q.
- (d) Wrong: Q cannot be shown to be heavier than P.
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.
Source: UPSC, Civil Services (Preliminary) Examination 2026, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.