Question

A man went to a place at the speed of 4km/h and came back at the speed of 16km/h .his average speed for the entire journey was?

Answer 1

10
km/hr is the average speed

formalae= v+u/2

=4+16/2=10km/hr

Answer 2

Let the distance between where he is now and the place be : x
Speed 1 : 4km/hr
Speed 2: 16km/hr
Time 1 : x/4
Time 2: x/16

Total Time :
$\frac{x}{4} + \frac{x}{16} = \frac{5x}{16}$
Total distance = x + x = 2x

AVG SPEED = 2x ÷ 5x/16
= 32/5

= 6.4 km/hr