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Q20·CSAT · Prelims 2022

Calculating successive percentage changes

NumericalPercentagesFactual singleEasy

Question

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?

Options

a

5%

b

10%

Answer
c

12.5%

d

15%

Explanation

Apply the successive percentage changes sequentially onto a standard baseline value of 100.

1Initial Price = 100.
2Increased by 25\%:

New Price = 100 + 25 = 125.

3Decreased by 20\%:

Decrease Amount = 20\% of 125 = 0.20 × 125 = 25. New Price = 125 - 25 = 100.

4Increased by 10\%:

Increase Amount = 10\% of 100 = 10. Final Price = 100 + 10 = 110.

Compare the final price back to the initial baseline: Resultant Increase = 110 - 100 = 10. Relative to 100, this is exactly a 10\% net increase.

A +25\% increase followed by a -20\% decrease perfectly cancel each other out (1.25 × 0.80 = 1.0), instantly resetting the value back to its original baseline.

Answer: (b).

Question details

Year

2022

Paper

CSAT

Question

Q20

Section

Numerical Ability

Sub-topic

Percentages

Type

Factual single

Difficulty

Easy

Source hint

Increase 25%, decrease 20%, increase 10%

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