The length of a rectangle is increased by 20% and its breadth by 10%. By what percentage does its area increase?

2%Correct answerYour answer30%Correct answerYour answer32%Correct answerYour answer132%Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer C

Correct answer: C

Area multiplies by $1.2 \times 1.1 = 1.32$ .
So the area increases by 32%. (Formula: $20 + 10 + \frac{20 \times 10}{100} = 32$ .)

Worth noting

Adding the two changes gives 30%, missing the extra $\frac{ab}{100} = 2\%$ .

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