Question 750129
A motorboat can go 12 miles downstream on a river in 20 minutes. 
It takes 30 minutes for this boat to go back upstream the same 12 miles. 
Whats the speed of the boat in still water?
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Downstream DATA:
dist = 12 miles ; time = 1/3 hr ; rate = d/t = 36 mph
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Upstream DATA:
dist = 12 miles ; time = 1/2 hr ; rate = d/t = 24 mph
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Equation:
Downstream: b + c = 36 mph
Upsteam ::: b - c = 24 mph
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Solve for "b":
2b = 60 mph
b = 30 mph (speed of the boat in quiet water)
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Solve for "c":
2C = 12 mph
c = 6 mph (speed of the current)
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Cheers,
Stan H.
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