2024 CSAT, all questions
UPSC Prelims 2024 · CSAT
Question 27: Basic Numeracy
A number is mistakenly divided by 4 instead of multiplying by 4. What is the percentage change in the result due to this mistake?
a25%
b50%
c72·75%
d93·75%
AnswerUPSC’s answer is (d).
Let the number be N. The intended result is 4N. The actual result is N/4. The change is 4N − N/4 = 15N/4. As a percentage of the correct result: (15N/4) ÷ 4N = 15/16 = 93.75%, a decrease. Remember: percentage change is always measured against the correct, original value, not the new one.
Why each option is right or wrong
- (a) Wrong. 25% is not the change in the result; the result falls to 1/16 of the correct value.
- (b) Wrong. 50% does not match 15/16.
- (c) Wrong. 72.75% does not match 15/16.
- (d) Right. 15/16 = 0.9375, i.e. 93.75%.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2024, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.