Question

The sides of a rectangular piece of card are each $10$ per cent too long for a particular project. By what percentage is the area too large?

• A. $19\%$
• B. $20\%$
• C. $21\%$
• D. $22\%$

Answer 1

The correct option is C $21\%$

Let each side of a rectangular piece of card is $100$ cm

$\therefore$ Area of rectangular peice $=$ $100\times 100$

$=10000c{m}^2$

If the sides of a rectangular piece of the card is increase $10\%$, then the side is $110$ cm

$\therefore$ Area $=$ $110\times 110$

$=12100c{m}^2$

Difference of the area $=12100-10000=2100$

Percentage increase in the area $=$ $\frac{2100}{1000}\times 100$

$=21$ $\%$