Question

a boy swims in a 100m long pool. he covers 60m with a velocity of 20m/s and covers the rest of the distance with a velocity of 10m/s. calculate the average speed of the boy.

Answer 1

Average speed = Total distance covered / Total time taken
Total distance = Length of pool = 100 m
Total time taken = (60/20) + (40/10)
= 3+4 = 7 second
Average speed = 100/7 = 14.285714.....

Hope this helps :)

Answer 2

Total distance = 100m.
To cover 60m with velocity of 20m/s time taken=60/20=3
Then rest distance is 100-60=40 and to cover that distance time taken=40/10=4
Total time=3+4=7
average speed=Total distance/Total time=100/7=14.285..
Hope it helps.