A man travels 120 km at 40 km/h and returns the same distance at 60 km/h. What is his average speed for the whole journey?
Show answer & explanation
Correct answer: A
Explanation
Given:
First distance = 120 km
First speed = 40 km/h
Second distance = 120 km
Second speed = 60 km/h
Formula:
Average speed = Total distance ÷ Total time
First part time = 120 ÷ 40 = 3 hours
Second part time = 120 ÷ 60 = 2 hours
Total distance = 120 + 120 = 240 km
Total time = 3 + 2 = 5 hours
Average speed = 240 ÷ 5 = 48 km/h