Question

A motor boat covers a certain distance downstream in 30 mins while it comes back in 45 minutes if the speed of the stream is 5 kmph what is the speed of the boat in still water ??

Answer 1

Let the speed of the boat in still water be x

So speed in down stream = x+5kmph

Speed in up stream =x-5kmph

Time taken = 30 Min = 30/60 hr

Time taken in up stream = 45/60 hr

Distance will remaine Same

So d1 = x+5* 30/60

D2 = x-5*45/60

So

X + 5* 1/2 = x- 5 * 3/4

= 4x +20= 6x -30

= -2x = -50

=x 25kmph

So the speed of the boat in still water is 5kmph