<PRE><B>Question 930543</B>
x = speed of boat in still water
y = speed of current = 4 mph
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s = d/t
t = d/s
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upstream:
t = 3/(x - y)
t = 3/(x - 4)
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downstream:
t = 11/(x + y)
t = 11/(x + 4)
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equate times:
3/(x - 4) = 11/(x + 4)
3(x + 4) = 11(x - 4)
3x + 12 = 11x - 44
8x = 56
x = 56/8
x = 7
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answer:
x = speed of boat in still water = 7 mph
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