Question

A car travels a certain distance of 50 km/h and returns at a speed of 40km/h. calculate the average speed for the whole journey

Answer 1

Let the certain distance be x km.

as speed = 50 kmph

so, time = x/50 h

In return , speed = 40 kmph

so, time = x/40 h

As average speed = total distance /total time

and total distance = 2x

total time= x/50 + x/40 = (4x+5x)/200 = 9x/200

So, average speed = 2x / (9x/200)

= 2x×200 / 9x = 400/9 kmph

= 44.44 kmph.

So, average speed of the whole journey is 44.44 kmph.