Two bus start from a house at an interval of 10 minutes and travel at a speed of 20 km/hr. With how much speed (km/hr). should a man coming from the opposite direction towards the house travel, to meet the buses at an interval of 8 minutes?

Show answer & explanation

Answer: (A) 5

Explanation

Buses leave 10 minutes apart at 20 km/h, so they are 20 × 10/60 = 10/3 km apart. The man meets them every 8 minutes, so the relative speed (20 + v) × 8/60 = 10/3, giving 20 + v = 25 and v = 5 km/h.