Question

Boojho walks to his school which is at a distance from his home in $30$ minutes. On reaching he finds that the school is closed and comes back by bicycle with his friend and reaches home in $20$minutes. His average speed in $\mathrm{km}/\mathrm{h}$ is

• A. $8.3$
• B. $7.2$
• C. $5$
• D. $3.6$

Answer 1

The correct option is B

$7.2$

Step 1: Given data:

1. Boojho walks to his school, which is at a distance of 3 km from his home, in 30 minutes.
2. He comes back by bicycle with his friend and reaches home in 20 minutes.

Step 2: Formula used:

Average speed = Total distance / Time taken

Step 3: Calculate and apply:

Boojho Home to school, then back home
The distance from home to school is $3\mathrm{km}$, and the time required is $30$ minutes = $\left(\frac{30}{60}\right)$ hour = $0.5$hour.

And the time is taken to get from school to home = $20$ minutes =$\left(\frac{20}{60}\right)$hour = $0.33$hour

Average speed = Total distance / Time taken

= $\frac{3+3}{0.5+0.33}\mathrm{km}/\mathrm{h}$

= $\text{7.2 km/h}$

Hence, option (B) is the correct answer.