Question

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:

• A. 10%
• B. 10.08%
• C. 20%
• D. 28%
• E. None of these

Answer 1

The correct option is D

28%

Let original length = `x' and original breadth = `y' Decrease in area = xy -- $\left(\frac{80}{100}x\times \frac{90}{100}y\right)=\left(xy-\frac{18}{25}xy\right)=\frac{7}{25}xy$ $\therefore$ Decrease % = $\left(\frac{7}{25}xy\times \frac{1}{xy}\times 100\right)$