A boat covers 24 km upstream & 36 km downstream in 6 hours while covers 36 km upstream & 24 km downstream is 6.5 hours..

Question

A boat covers 24 km upstream and 36 km downstream in 6 hours, while it covers 36 km upstream and 24 km downstream is 13/2 hours. What is the velocity of the current?

Answer 1

For the First case
[ As time = distance / speed ]
[ Also let velocity of boat be 'b' and that of the stream be 's' ]
(24/(b-s))+(36/(b+s))=6 ----1
and for the second case
(36/(b-s))+(24/(b+s))=6.5 ---2

Now from 1 - 2
and 1 + 2

we can easily get

b/s=5/1
ie., b=5s ( boat's speed is 5 times greater than that of the stream ) ---3

substituting 3 in (1 - 2)
yields s= 2 km/hr.