Speed of a boat in still water is 18 km/hr and the speed of the stream is 3 km/hr. A man sails a distance of 105 km and comes back to the starting point. The total time taken is

Options
- 12 hours
- 18 hours
- 24 hours
- 30 hours

CORRECT ANSWER : 24 hours

Discussion Board
answer is wrong

upstream speed=boat speed-stream speed
u/s=18-3=15 km/hr
downstream speed =boat speed +stream speed
d/s =18+3=21 km/hr
distance/speed=time
time take to row u/s=105/15=7 hrs (km/(km/hr)=hr)
time taken to row down stream=105/21=5hrs
time taken to row up and down=7+5=12hrs




apoorva 03-1-2018 01:38 AM

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