A number is mistakenly divided by 4 instead of multiplying by 4. What is the percentage change in the result due to this mistake?
Answer & explanation
Answer: (d) 93.75%
The correct result is 4x and the mistaken one x/4. The result falls by 4x − x/4 = 15x/4, which is 15/16 of the correct result, i.e. 93.75%.
- Take the number as 16. Correct result = 16 × 4 = 64; mistaken result = 16 ÷ 4 = 4.
- Change = 64 − 4 = 60.
- Percentage change = 60/64 × 100 = 93.75% (a fall).
- Check in general: (4 − 1/4)/4 = 15/16 = 0.9375.
Remember · Pick a convenient number and measure the change against the correct result, which is the base.
Question and answer: UPSC's official GS Paper II (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·