A person covers 48 km at the speed of 8 km/h, 36 km at the speed of 18 km/h and 16km at the speed of 8 km/h. What is his average speed in covering the whole distance?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 10 km/h.
Time 1 = 48/8 = 6 hours
Time 2 = 36/18 = 2 hours
Time 3 = 16/8 = 2 hours
Total distance = 48 + 36 + 16 = 100 km
Total time = 6 + 2 + 2 = 10 hours
Average speed = Total distance/Total time = 100/10 = 10 km/h