Question

If the speed of a boat in still water is 60 km/h. If the boat travels 180 km along the stream in 2 hours 30 minutes, then the time taken by it to cover the same distance against the stream will be?

Answer 1

Let the speed of the stream be x

Speed in still water = 60km/h

Downstream:

Speed = (60 + x) km/h

Distance = Speed x Time

180 = 2.5(60 + x)

Solve x:

180 = 2.5(60 + x)

180 = 150 + 2.5x

2.5x = 30

x = 12 km/h

Upstream:

Speed = ( 60 - 12 ) = 48 km/h

Distance = 180 km

Time =  Distance ÷ Speed

Time = 180 ÷ 48 = 3.75 hour or 3 hours 35 mins

Answer: It takes 3 hours 45 mins to travel against the stream.