A car driver travels from the plains to a hill station, which are 200 km apart at an average speed of 40 km/h. In the return trip he covers the same distance at an average speed of 20 km/h. The average speed of the car over the entire distance of 400 km is

Options

A. 16.56 km/h
B. 17.89 km/h.
C. 26.67 km/h.
D. 35 km/h.

Answer

C

Explanation

Average speed of entire distance of 400 km
`= ("Total distance")/("Total time")`
= `(200 + 200)/((200)/(40) + (200)/(40)) = (400)/(5 + 10) = (400)/(15) = 26.67` km/h