Question

find the speed of the boat in still water

Answer 1

Given that,
speed of current in stream=4km/hr
Let the distance covered by boat be 'y'
and speed of boat be xkm/hr.
We know that,
Then,
speed of boat in upstream=x-4
and
speed of boat in downstream=x+4
Time taken=distance covered/speed of boat.

Time taken by boat to cover distance ykm in upstream = y/(x-4)

Time taken by boat to cover distance ykm in downstream = y/(x+4)
As per given condition we have,
y/(x-4) = 5[y/(x+4)]

1/(x-4) = 5/(x+4)

x+4 = 5x-20

4x=24

x=6


Hence speed of boat in
still water = 6km/hr.

Answer 2

Hello sir!!

See the attached pic!

Hope it helps..!!