Question

A person, rowing at the rate of 5 km/h in still water, takes thrice as much time in going 40 km upstream as in going 40 km downstream. Find the speed of the stream. hours. Find the speed of the boat in still water and the speed of the stream.

Answer 1

Speed in still water=5 km/h

Speed of the stream=x km/h

Time taken going downstream=40/(5+x) hours

Time taken going upstream=40/(5-x) hours

Time taken going upstream is three times the time taken going downstream

40/(5-x)=3[40/(5+x)]

40/(5-x)=120/(5+x)

200+5x=600-120x

125x=400

x=3.2 km/h

Hence,

speed of stream=3.2 km/h