Question

A car travels a certain distance with a speed of 50 km/h and return with a speed of 40 km/h.calculate av.speed

Answer 1

average speed of the car is equal to (40 km/ hour + 50 km/ hour) / 2.
so, (90km/h)/2
hence your ans is. 45km/h.

HOPE THIS HELPS U.

Answer 2

Let the distance between the two specified destination be $d$.
Then,initial time taken for the car to travel the distance$=t_1=\frac{d}{50km/h}$
Time taken for the car to travel back to its initial position$=t_2=\frac{d}{40km/h}$
Average Speed is the ratio of total distance covered and total time taken.$\langle|v|\rangle=\dfrac{\sum_{i}d_i}{\sum_{i}t_i}\\=\dfrac{2d}{t_1+t_2}\\=\dfrac{2d}{\dfrac{d}{50}+\dfrac{d}{40}}\\=\dfrac{2}{\dfrac{4+5}{200}}=\dfrac{400}{9}=44.44km/h$