Question

Excluding stoppages, the speed of a school bus is 48 kmph and including stoppages, it is 40 kmph. For how many minutes does the school bus stop per hour?

• A. 7 min
• B. 8 min
• C. 9 min
• D. 10 min
• E. 6 min

Answer 1

The correct option is D

10 min

The average speed (including stoppage) is 40km/hr
Distance = $speed\times time$
So, in ONE hour, the distance traveled = $40\times 1$ = 40 km

The average speed (excluding stoppage) is 48 km/hr
time = $\frac{distance}{rate}$
So, time = $\frac{40}{48}$
= $\frac{5}{6}$ hours
= 50 minutes

At a speed of 48 km per hour, the bus can travel 40 km every 50 minutes.
So, it must be motionless for the other 10 minutes.