UPSC Prelims 2022 CSAT Paper II · Q20 of 78 Basic Numeracy easy

The increase in the price of a certain item was 25%. Then the price was decreased by 20% and then again increased by 10%. What is the resultant increase in the price?

  1. (a) 5%
  2. (b) 10% ✓ UPSC's answer
  3. (c) 12.5%
  4. (d) 15%

Why the answer is (b)

• Let the initial price of the item be 100.

• After a 25% increase, the price becomes 100 + 25 = 125.

• A subsequent 20% decrease on 125 is 25, making the new price 125 - 25 = 100.

• A final 10% increase on 100 is 10, resulting in a final price of 110.

• The net change is from 100 to 110, which is a 10% increase.

• Therefore, the resultant increase in the price is 10%.

Why the other options are wrong

(a) 5%
5% is incorrect because the final price is 110, representing a 10% increase, not 5%.
(c) 12.5%
12.5% is incorrect because the final price is 110, representing a 10% increase, not 12.5%.
(d) 15%
15% is incorrect because the final price is 110, representing a 10% increase, not 15%.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

Reading the answer is not the same as getting it right under a clock. Practise this question with UPSC's negative marking, and anything you miss goes into an error notebook until you get it right twice.

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