A train runs at a speed of 90 km/h in the first 10 minutes and 60 km/h in next 25 minutes and 15 km/h in last 4 minutes. What is the average speed of the train?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. km/h.
We know that,
Average Speed = Total Distance/Total Time
Distance covered at the speed of 90 km/hr in 10 minutes
Distance = 90 × 10/60 = 15 km
Distance covered at the speed of 60 km/hr in 25 minutes
Distance = 60 × 25/60 = 25 km
Distance covered at the speed of 15 km/hr in 4 minutes
Distance = 15 × 4/60 = 1 km
Total distance = 15 + 25 + 1 = 41 km
Total Time = (10 + 25 + 4) = 39/60
Average Speed = 41/39/60 = 41 × 60/39 = 820/39 = km/hr