How many seconds will a boy take to run one complete round around a square field of side 18 metres, if he runs at a speed of 6 km/h?

Correct option is D

Given:

Side of square field = 18 m

Speed of boy = 6 km/h

Need: Time to run one complete round

Formula Used:

Perimeter of square = 4 × side

Time =$$\dfrac{\text{Distance}}{\text{Speed}}$$​​

Solution:

Perimeter of field = 4 × 18 =72 m

Convert speed:

​$$6 \times \frac{5}{18} = \frac{30}{18} = 1.67 \ \text{m/s}$$​

Time taken:

Time =$$\frac{72}{1.67} \approx 43.2 \ \text{seconds}$$​