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CSAT 2021 paper

UPSC CSE CSAT 2021 · Question 78 · Arithmetic: percentage, ratio, averages, time & work

If the price of an article is decreased by 20% and then the new price is increased by 25%, then…

If the price of an article is decreased by 20% and then the new price is increased by 25%, then what is the net change in the price?

Answer & explanation

Answer: (a) 0%

A 20% cut takes ₹100 to ₹80, and 25% of 80 is 20, bringing it back to ₹100. The multipliers 0.8 × 1.25 = 1, so there is no net change.

  1. Let the price be ₹100. After a 20% decrease it is ₹80.
  2. A 25% increase on ₹80 is ₹20, giving ₹100.
  3. Net change = 0%.
  4. Check: 0.8 × 1.25 = 1.

Remember · Successive changes multiply: a fall of 1/5 is exactly undone by a rise of 1/4.

Question and answer: UPSC's official GS Paper II (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·

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