Question

A boy runs for 10 min at a uniform speed of9km/hr. At what speed should he run for next 20 min so that average speed comes to 12 km/hr

Answer 1

Explanation:

Hey Mate

t=10min=600sec

speed = 9km/h=9*5/18=5/2m/s or 2.5m/s

Average Speed = v1 +v2/2

v1=2.5m/s

v2=?

Average Speed=12km/h=12*5/18=20/6=10/3m/s

10/3=2.5+v2

v2=10/3-5/2

v2=20-15/6

v2=5/6 m/s