UPSC Prelims 2026 · CSAT
Question 43: Basic Numeracy
A person saves 10% of his salary every month. If his salary increases by 12% and the expenditure increases by 10%, then what will be the change in his saving per month?
AnswerUPSC’s answer is (b).
Let the salary be 100: saving 10, expenditure 90. The new salary is 112 and the new expenditure is 90 × 1.10 = 99, so the new saving is 13. The change is (13 − 10)/10 = 30%, an increase. Saving changes by a much larger percentage than salary because it is a small difference of two large numbers.
Why each option is right or wrong
- (a) Wrong: a 20% rise would mean a new saving of 12.
- (b) Right: saving rises from 10 to 13.
- (c) Wrong: saving rises; it does not fall.
- (d) Wrong: saving rises; it does not fall.
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.