A boy goes to his school from his house at a speed of 3 km / hr and returns at a speed of 2 km / hr. If he takes 5 hours in going and coming, the distance between his house and school is :___________?

A. 5 km
B. 5.5 km
C. 6 km
D. 6.5 km

Average speed = ( 2 X 3 X 2/3 + 2 ) km/ hr = 12/5 km/ hr. Distance travelled = ( 12/5 X 5 )km = 12 km. So Distance between house and school = ( 12/2 )km = 6 km.