A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will he take to go 5km in stationery water?

A. 40 Minutes
B. 1 Hour
C. 1 hr 15 Min
D. 1 Hr 30 Min
Explanation:
Speed upstream = 2km/hr.
Speed downstream = 6 km/hr
Speed in stationary water = ½ (6 + 2) km/hr = 4 km/hr
Time is taken to cover 5 km in stationary water
= (1/4 x 5) 1 hr 15 min