Question

A person takes 5 hours to dig a 1 m deep hole. Under the same conditions, he will take hour(s) to dig a 20 cm deep hole.

• A. 100
• B. 50
• C. 1
• D. 2

Answer 1

The correct option is C 1

Depth ∝ Time

We know that, if two quantities are directly proportional, then the ratio between the two quantities is constant.

$\frac{depth}{time}$ = constant

We know, 1 m = 100 cm

$\begin{array}{ccc}\text{Depth(cm)}& \text{100}& 20\\ Time\left(hr\right)& 5& ?\end{array}$

$\frac{100}{5}=\frac{20}{x}$

$x=1hour$