Question

For how many minutes does a city bus stop per hour, If including the stoppages the city bus travels at a speed of 60 km/hr and excluding stoppages the speed of city bus is 81 km/hr.

1. 10.5 minutes 
2. 20.5 minutes 
3. 15.5 minutes 
4. 19 minutes 
5. None of these

Answer 1

Correct Answer - Option 3 : 15.5 minutes 

Given:

Speed of Bus without stoppage is 81 km/h and with stoppage is 60 km/h

Concept:

Stoppage time = Speed difference/speed without stoppage 

Calculation:

The speed of a bus without stoppages  = 81 km/hr

The speed of  a bus with stoppages = 60 km/hr

Speed difference = 81 - 60 

⇒ 21 km/hr

Stoppage time = Speed difference/speed without stoppage 

Stoppage time = 21/81 hours

Stoppage time =  7/27 hr

Stoppage time =  (7/27) × 60 min

Stoppage time = 15.5 min.

∴ The bus stop 15.5 min in one hours.