The length of a rectangular plot is increased by 15% and its breadth is decreased by 20%. What happens to its area?

It decreases by 8%Correct answerYour answerIt decreases by 5%Correct answerYour answerIt decreases by 3%Correct answerYour answerIt increases by 3%Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

Area multiplies by $1.15 \times 0.8 = 0.92$ .
So the area decreases by 8%. (Formula: $15 - 20 + \frac{15 \times (-20)}{100} = -8$ .)

Worth noting

$15 - 20 = -5$ misses the cross term of −3.

Concept: Area change when one side grows and the other shrinks
Typical timeTypical: 55 s
Your timeYours: —

The rule this testsSuccessive percentage change

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Ten questions from Percentages, at your own pace.

The length of a rectangular plot is increased by 15% and its breadth is decreased by 20%. What happens to its area?

Explanation