Question 1115356
 The speed of a stream is 4 mph. A boat travels 11 miles upstream in the same time it takes to travel 19 miles downstream. What is the speed of the boat in still​ water? 
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Upstream DATA:
dist = 11 miles ; rate = b-4 mph ; time = d/r = 11/(b-4)
Downstream DATA:
dist = 19 miles ; rate = b+4 mph ; time = d/r = 19/(b+4)
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Equation:
time up = time down
11/(b-4) = 19/(b+4)
11b+44 = 19b - 76
8b = 120
b = 15 mph (speed of the boat in calm water)
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Cheers,
Stan H.
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