A boy goes to school at a speed of 3 km/hr and returns to the village at a speed of 2 km/hr. If he takes 5 hrs in all, what is the distance between the village and the school?

If the distance is d km, the trip to school takes d/3 hours and the return d/2 hours, so d/3 + d/2 = 5, which gives 5d/6 = 5 and d = 6 km. Check: 2 hours going and 3 hours returning make 5 hours; 7, 8 or 9 km would take longer than 5 hours.