Question

Ram goes from A to B by auto at the speed of 20km/hrs and comes back from B to A in a cab at the speed of 80km/hrs. Find his average speed ?

Answer 1

since equal distances are covered at 20 kmph and 80 kmph, we can apply the formula 2xy/(x+y)

Average speed= 2x20x80/(20+80)= 32 kmph

This formula works as follows

Let the distance to one side = x
Total distance = 2x

Time taken for the forward journey = x/20
Time taken for the return journey = x/80
Total time = x/20+x/80= 5x/80 = x/16

Average speed = Total distance/Total Time=2x/(x/16) = 32kmph