Question

The length of a rectangular whiteboard is 20 cm. Its area is 100 sq. cm. Find its width.

• A. $10$ cm
• B. $5$ cm
• C. $15$ cm
• D. $3$ cm

Answer 1

The correct option is B $5$ cm

Let, the width of the whiteboard is $w.$

Given, area of the whiteboard = 100 sq. cm.
Length of the whiteboard = 20 cm

$\because \text{Area of a rectangle = length × width}$
$\Rightarrow 100=20\times w$
Divide both sides by 20
$\Rightarrow \frac{100}{20}=\frac{20\times w}{20}$
$\Rightarrow 5=w$
$\Rightarrow w=5$ cm
Therefore, option (b.) is the correct choice