SOLUTION: Gone fishing. Debbie traveled by boat 5 miles upstream to
fish in her favorite spot. Because of the 4-mph current, it
took her 20 minutes longer to get there than to return. How
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-> SOLUTION: Gone fishing. Debbie traveled by boat 5 miles upstream to
fish in her favorite spot. Because of the 4-mph current, it
took her 20 minutes longer to get there than to return. How
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Question 202323This question is from textbook Elementary and Intermediate Algebra
: Gone fishing. Debbie traveled by boat 5 miles upstream to
fish in her favorite spot. Because of the 4-mph current, it
took her 20 minutes longer to get there than to return. How
fast will her boat go in still water? This question is from textbook Elementary and Intermediate Algebra
You can put this solution on YOUR website! Debbie traveled by boat 5 miles upstream to
fish in her favorite spot. Because of the 4-mph current, it
took her 20 minutes longer to get there than to return. How
fast will her boat go in still water?
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Upstream DATA:
distance = 5 miles; time = x + 20 ; rate = d/t = 5/(x+2) hrs.
---------------------------
Downstream DATA:
distance = 5 miles ; time = x ; rate = d/t = 5/x
----------------------------
Equation:
rate upstream = b-4=5/(x+2)
rate downstrea= b+4=5/x
--------------------------
Subtract 1st from 2nd to get:
8 = 5/x - 5/(x+2)
Solve for "x":
8x(x+2) = 5(x+2) - 5x
8x^2+16x = 10
4x^2+8x-5 = 0
4x^2+10x-2x-5 = 0
2x(2x+5)-(2x+5) = 0
(2x+5)(2x-1) = 0
Positive solution:
x = 1/2
---------------------
Solve for "b" when b+4 = 5/x
b+4 = 5/(1/2)
b+4 = 10
b = 6 mph (speed of the boat in still water)
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Cheers,
Stan H.
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