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 it take to go 5 km in stationary water ? Choose the correct choice from the following answers
A) 40 minutes B) 1 hour C) 1 hr 15 min D) 1 hr 20 min E) None of these
Solution   Rate downstream =(1/10x60) km/hr = 6 km/hr, Rate upstream = 2 km/hr.   Speed in still water =1/2(6 + 2) km/hr = 4 km/hr.   ∴ Required time =(5/4)hrs = 1 1/4hrs = 1 hr 15 min. Answer 1 hr 15 min
<result>C</result>
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 it take to go 5 km in stationary water ?