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A steamer goes downstream from one point to another in 9 hours. It covers the same distance upstream in 10 hours.
If the speed of the stream be 1 km/hr , find the speed of the steamer in still water and the distance between the ports .
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Let D be the distance between the ports (in kilometers), and
let u be the streamer speed in still water.
Then you have these two equations
= u + 1, (1) ( speed equation for moving downstream )
= u - 1, (2) ( speed equation for moving upstream )
Distract equation (2) from (1) (both sides). You will get
= 2 ---> = 2 ---> = 2 ---> D = 2*90 = 180.
Thus we found the distance. It is 180 kilometers.
Now from (1),
= u + 1 ---> 20 = u + 1 ---> u = 20-1 = 19.
The treamer speed in still water is 19 .