Question 7

Length and breadth of a rectangle are increased by 40% and 70% respectively. What will be the percentage increase in the area of rectangle?

Solution

Let length and breadth of rectangle initially be $$10$$ units

=> Area, $$A=10\times10=100$$ sq.units

Length is increased by 40%, => New length = $$10+(\frac{40}{100}\times10)=14$$ units

Similarly, new breadth = $$10+(\frac{70}{100}\times10)=17$$ units

=> New area, $$A'=14\times17=238$$ sq.units

$$\therefore$$ % increase in area = $$\frac{(238-100)}{100}\times100=138\%$$

=> Ans - (C)

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