A person walks 10 km at a speed of 2.5 km per hour, then runs 10 km at a speed of 5 km per hour and then goes 30 km by bus at the speed of 30 km per hour. What is the average speed of the man?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 7.14 kmph.
The total distance traveled is = 10 km (walking) + 10 km (running) + 30 km (by bus) = 50km
Time taken to walk 10 km at 2.5 km/h = Distance/Speed = 10/2.5 = 4 hours
Time taken to run 10 km at 5 km/h = Distance/Speed = 10/5 = 2 hours
Time taken to travel 30 km by bus at 30 km/h = Distance/Speed = 30/30 = 1 hour
Total time = 4 hours + 2 hours + 1hour = 7 hours
The average speed = Total distance/Total time = 50 km/7 hours = 7.14kmph