SOLUTION: The Hudson River flows at a rate of 3mph. a Patrol boat travels 60mi upriver and returns in a total time of 9 hr. What is the speed of the boat in still water?

Question 143308This question is from textbook
: The Hudson River flows at a rate of 3mph. a Patrol boat travels 60mi upriver and returns in a total time of 9 hr. What is the speed of the boat in still water? This question is from textbook

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The Hudson River flows at a rate of 3mph. a Patrol boat travels 60 mi upriver and returns in a total time of 9 hr. What is the speed of the boat in still water?
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Let "b" be the speed of the boat in still water.
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Upriver DATA:
distance = 60 mi ; rate = b-3; time = d/r = 60/(b-3) hrs.
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Downriver DATA:
distance = 60 mi ; rate = b+3 ; time = 60/(b+3) hrs.
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EQUATION:
time + time = 9 hrs.
60/(b-3) + 60/(b+3) = 9
60b+180 + 60b-180 = 9(b^2-9)
120b = 9b^2-81
3b^2 - 40b - 27 = 0
Using a calculator I get b = 13.97 mph
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Cheers,
Stan H.

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