Question

a car travels from a to Bat aspeed of 20km/h and returns at a speed of 30km/h. the average speed of a car for whole joney is?

Answer 1

Let, S be the total distance travelled.

At first it travels distance S with speed 20 km/h. Time taken is = (S/20) hr

Then it returns with speed 30 km/h. Time taken is = (S/30) hr

So, total distance travelled is = 2S

Total time taken is = (S/20) + (S/30) = S/12

Average speed = 2S/[S/12] = 24 km/h