A motor boat whose speed is 18 km/h m still water takes 1 hour more to go 24 km upstream than to return downstream to the same spot. Find the speed of the stream.

Answer

6 km/hr

Explanation

Let the speed of the stream be x km/hr.
Then, speed downstream `=(18+x)km//hr`
and speed upstream `=(18-x)km//hr.`
`:." "(24)/((18-x))-(24)/((18+x))=1implies(1)/((18-x))-(1)/((18+x))=(1)/(24)`
`impliesx^(2)+48x-324=0impliesx^(2)+54x-6x324=0.`