The car delivered the cargo from point A to point B, moving at average speed `mu_(1)=40km//h`. Turning back, the car was moving at an average speed of `v_(2)=60km//h`.

Options

A. The average speed of its movement all the way is `50km//hr`
B. The average speed of its movement all the way is `52km//hr`
C. The average speed of its movement all the way is 0
D. The average speed of its movement all the way is `48km//hr`

Answer

D

Explanation

`t_(1)=(x)/(40),t_(2)=(x)/(60)`
`v_(av)=(2x)/(t_(1)+t_(2))=(2x)/((x)/(40)+(x)/(60))=(2xx60xx40)/(100)=48km//hr`