A man travels a distance of 2 km by walking at a speed of 6 km/hr. He returns back at a speed of 4 km/hr. What is his average speed?

A. 4.5 kmph
B. 4.8 kmph
C. 5 kmph
D. 5.1 kmph
Time taken for the forward journey
= 2/6 = (1/3) hrs Time taken for the return journey
= 2/4 = (1/2) hrs Total time = 5/6 hrs Average speed = 4/(5/6) = 24/5 = 4.8kmph