The speed of a bus is 60 km/hr including stoppages and 72 km/hr excluding stoppages. For how many minutes does the bus stop per hour?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 10 minutes
Because of the stoppages, the bus covers in one hour only the distance it would cover while moving at 72 km/hr. The time it does not need for moving is the time it stands still.
Distance covered in one hour, stoppages included \(=60\) km
Time needed to cover 60 km while moving \(\displaystyle =\frac{60}{72}\) hour \(=50\) minutes
Time spent at stoppages \(=60-50=\) 10 minutes per hour
Tip: Stoppage time per hour \(\displaystyle =\frac{\text{difference of the speeds}}{\text{speed without stoppages}}\times60\) minutes \(\displaystyle =\frac{12}{72}\times60=10\) minutes.