A man can row three-quarters of a kilometre against the stream in 11 1/4 minutes and down the stream in 7 1/2 minutes. The speed (in km/hr) of the man in still water is:_________?
Q1. A man can row three-quarters of a kilometre against the stream in 11 1/4 minutes and down the stream in 7 1/2 minutes. The speed (in km/hr) of the man in still water is:_________?
Answer: 5 km/hr
Explanation: Upstream speed = 0.75 km ÷ (11.25/60) hr = 4 km/hr; downstream = 0.75 ÷ 0.125 = 6 km/hr. Still water speed = (4+6)/2 = 5 km/hr.