A man walks from A to B at 5 km/h and returns from B to A at 4 km/h. What is his average speed for the whole journey?
Show answer & explanation
Correct answer: A
Explanation
The distance for the outward and return journeys is the same; therefore, the average speed is:
Average speed = 2xy / (x + y)
Where x = 5 km/h, y = 4 km/h
Average speed = 2 × 5 × 4 / (5 + 4)
= 40/9
= 4.4 km/h