A boy is travelling from his home to school at 5km/hr and reached 5min late. Next day he travelled at 10km/hr and reached 10min early. Distance between home and school?
Choose the most appropriate option:
A) 2.5 km B) 3 km C) 4 km D) 5.6 km E) 6.5 km

Rationale: "let the distance be x t 1 = x / 5 hr t 2 = x / 10 hr difference in time = 5 + 10 = 15 = 1 / 4 hr x / 5 - x / 10 = 1 / 4 x / 10 = 1 / 4 x = 2.5 km answer is a"
Answer: A