A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth. The percentage of decrease in area is:
10%
10.08%
20%
28%
Explanation:
Let original length = $x$ and original breadth = $y$.
| Decrease in area | = $x$$y$ -$ \left(\dfrac{80}{100} x \times \dfrac{90}{100} y\right) $ |
| =$ \left(xy -\dfrac{18}{25} xy\right) $ | |
| =$ \dfrac{7}{25} xy $ |
| $\therefore$ Decrease % =$ \left(\dfrac{7}{25} xy \times\dfrac{1}{xy} \times 100\right) $%= 28%. |