Question

A train covers a distance of 20 km in 15 minutes. If its speed is increased by 10 km/hr, the time taken by it to cover the same distance will be:
1. 13 minutes 20 seconds
2. 12 minutes
3. 11 minutes 10 seconds
4. 10 minutes

Answer 1

Correct Answer - Option 1 : 13 minutes 20 seconds

Distance = 20km

Time = 15 minutes = 1/4 hr

∴ Speed of the train = Distance/Time

= 20/(1/4) = 80 km/h

After increasing its speed by 10 km/hr,

New speed = 90 km/hr

Distance = 20 km (given)

∴ Time = Distance/ Speed

∴ Time = 20/90 = 2/9^th of an hour = 60 × 2/9

Thus, the time taken by the train will be 13 minutes and 20 seconds.