A car travels with the speed of 40 km/hr for the first hour and 60 km/hr for the next hour. What will be the average speed of the car?

50 km/hr 

distance = speed x time

The distance covered at the speed of 40 km/hr in first hour = 40 x 1 = 40 km

The distance covered at the speed of 60 km/hr in second hour = 60 x 1 = 60 km

Average speed = $\frac{total \; distance}{total\; time}$

                       = $\frac{40+60}{2}$ = 50 km/hr