Boojho walks to his school which is at a distance of 3 km from his home in 30 minutes. On reaching he finds that the school is closed and comes back by bicycle with his friend and reaches home in 20 minutes. His average speed in km/h is
Boojho Home to school to again home
From home to school distance is 3 km time taken is 30 min = (30/60) hour = 0.5 hour
And in returning from school to home time taken = 20 min = (20/60) hour = 0.33 hour
average speed = Total distance / time taken
= (3 + 3)/(0.5 + 0.33) km/h
= 7.2 km/h