# A man can row at 6 km/h in still water and at 4 km/h upstream. How long will the mantake to go to a place 1 km downstream and return

2
by mushinibharat2

• Brainly User
2014-10-28T22:12:05+05:30
Stream is flowering at a rate of 6-4=2km/h. Hence man can row downstream at 6+2=8km/h. This means he takes 1/8 of hour to go downstream and 1/4 of hour to go upstream separated by 1km. Total time taken is 1/8 + 1/4 = 3/8 of an hour i.e 22.5 minutes.
2014-10-29T11:56:54+05:30

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Speed of man in still water = 6 km/h
let the speed of river = v km/h
speed of man upstream = (6-v) km/h = 4 km/h
thus v = (6-4) km/h = 2 km/h
speed of the man downstream = (6+v) = (6+2) km/h = 8 km/h

to go 1 km downstream, time = 1/8 hour
to return 1 km upstream, time = 1/4 hour
total time = 1/8 + 1/4 = (2+1)/8 = 3/8 hours

So he will take 3/8 hours to go to a place 1 km downstream and return.