Question

a man Walks for one night at a speed of 1 metre per second and then runs for 1 net at a speed of 3 metre per second along a straight track what is the average speed of the man

Answer 1

May I know for how long did he walk(time)?
If that is provided you can use the formula

Average speed=
$\frac{speed \: final - \: speed \: initial}{total \: time }$