Question

A boat goes downstream covers the distance between two ports in 96 minutes.While it covers the same distance upstream in 120 minutes,if the speed of the stream is 1 km/hr.Find the speed of boat in still water.

Answer 1

Let the speed of the boat in still water be x kmph.
By given,
Distance, d is same
Speed of stream=1 kmph
Speed upstream=x-1 kmph
Speed downstream=x+1 kmph
we know,
distance=speed x time
since the distance is same, we get,
(x+1)96=(x-1)120
=> 96x+96=120x-120
=>      24x = 216
=>          x =9 kmph
Thus, speed of the boat in still water is 9 kmph.