A boat travels 40 km upstream in 4 hours and downstream in 2 hours. What is the speed of the stream?
Show answer & explanation
Correct answer: D
Explanation
40 km against the current = 4 hours
40 km with the current = 2 hours
Speed against the current = 40 / 4 = 10 km/h
Speed with the current = 40 / 2 = 20 km/h
Speed of the current = (20 − 10) / 2 = 10 / 2 = 5 km/h