<PRE><B>Question 65062</B>
If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hours, the rate of the river and the rate of the boat in still water respectively are ?
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Let b be the boat rate; s be the stream rate
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Downstream DATA: 
distance=72 miles ; time = 3 hrs ; rate= d/t=72/3=24 mph

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Upstream DATA:
distance = 72 miles ; time = 6 hrs; rate =d/t=72/6 = 12 mph
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EQUATIOn:
b+s=24
b-s=12
2b=36
b=18 mph (boat speed in calm water)
18+s=24
s=6 mph (stream speed)
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Cheers,
Stan H.
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