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When the length of a rectangle is increased by 20% and the width increased by 10%, by what percent is the area increased?

 Jan 26, 2018
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original area   =   L * W

 

new length   =   L + 20% * L   =   L + 0.2L   =   1.2L

new width   =   W + 10% * W   =   W + 0.1W   =   1.1W

 

new area   =   1.2L * 1.1W

new area   =   1.2 * 1.1 * L * W

new area   =   1.32 * L * W

new area   =   1.32 * original area

new area   =   (1 + 0.32) * original area

new area   =   original area + 0.32 * original area

new area   =   original area + 32% * original area

 

The new area is the original area increased by  32%  of the original area.

 Jan 26, 2018

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