Question 91212
A sailboat travels 20 miles downstream in 3 hours. It returns in 4 hours. Find the speed of the sailboat in still water and the rate of the current. 
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Draw the picture:
Symbolize the DATA:
Downstream DATA:
distance= 20 miles; time = 3 hrs ; rate = 20/3 hrs
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Upstream DATA:
distance = 20 miles; time = 4 hrs ; rate = 20/4 = 5 hrs
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Let speed in still water be "b"
Let speed of the current be "c"
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EQUATION:
b+c=20/3
b-c=5
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Add the two equations:
2b = 35/3
b = 35/6 mph (speed of the boat in still water)
Solve for c:
35/6 + c = 40/6
c=5/6 mph (speed of the current)
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Cheers,
Stan H.