Question 988734: Upstream, downstream, Katherine's boat will go 15 miles per hour in still water. If she can go 12 miles down stream in the same time it takes to go 9 miles upstream, then what is the speed of the current
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Upstream, downstream, Katherine's boat will go 15 miles per hour in still water. If she can go 12 miles down stream in the same time it takes to go 9 miles upstream, then what is the speed of the current
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Downstream DATA:
dist = 12 miles ; rate = 15+c mph ; time = d/r = 12/(15+c) hrs
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Upstream DATA:
dist = 9miles ; rate = 15-c mph ; time = d/r = 9/(15-c) hrs
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Equation:
time = time
12/(15+c) = 9/(15-c)
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12(15-c) = 9(15+c)
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12*15 - 12c = 9*15 + 9c
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21c = 3*15
c = (1/7)15
c = 2 1/7 mph (speed of the current)
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Cheers,
Stan H.
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