Percentage | Arithmetic aptitude | Discussion Page

The length of rectangle is increased by 10% and breadth is decreased by 10% .Then the area of the new rectangle

A) Neither increase nor decrease

B) Increased by 1 %

C) Decreased by 1%

D) Increased by 2%

E) Decreased by 2%

Option C

Originally let length $= x$ and breadth $= y$

Area of rectangle $= xy$

Increase in length $= x +\frac{10x}{100} = \frac{11x}{100}$

Decrease in length $= y – \frac{10y}{100} = \frac{9y}{10}$

New area $= \frac{99xy}{100} \Rightarrow$ Decrease in area $= xy-\frac{99xy}{100}$ $= \frac{xy}{100}$

Decrease % =$\frac{xy}{100}\div xy$

=1% decrease

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