A sailor goes 8 km downstream in 40 minutes and returns in 1 hours. Determine the speed of the sailor in still water and the speed of the current.

Answer

10 kmph, 2 kmph

Explanation

Let the speed of the sailor in still water be x kmph and the speed of the current be y kmph.
Then, speed downstream = ` (x + y ) ` km/hr.
And, speed upstream = ` (x - y ) ` km/hr
` therefore (8)/(x + y ) = ( 40)/(60) = (2)/(3)rArr x + y = 12 " " `… (i)
and `(8)/(x - y ) = 1 rArr x - y = 8. " "`… (ii)
Solve (i) and (ii).