SOLUTION: Please help me with:
The speed of the current in a river is 2mph. Jay travels 20 miles upstream and then 20 miles downstream in a total time of 5 1/3 hours. Find the speed of
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-> SOLUTION: Please help me with:
The speed of the current in a river is 2mph. Jay travels 20 miles upstream and then 20 miles downstream in a total time of 5 1/3 hours. Find the speed of
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Question 170051: Please help me with:
The speed of the current in a river is 2mph. Jay travels 20 miles upstream and then 20 miles downstream in a total time of 5 1/3 hours. Find the speed of the boat.
Let s be the speed of the boat.
You can put this solution on YOUR website! The speed of the current in a river is 2mph. Jay travels 20 miles upstream and then 20 miles downstream in a total time of 5 1/3 hours. Find the speed of the boat.
Let s be the speed of the boat.
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Upstream DATA:
distance = 20 miles ; rate = s-2 mph ; time = d/r = 20/(s-2) hrs.
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Downstream DATA:
distance = 20 miles ; rate = s+2 mph ; time = d/r = 20(s+2) hrs.
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EQUATION:
time + time = 16/3 hrs
20/(s-2) + 20/(s+2) = 16/3
60(s+2) + 60(s-2) = 16(s^2 - 4)
120s = 16s^2 - 64
16s^2 - 120s - 64 = 0
2s^2 - 15s - 8 = 0
s = [15 +- sqrt(225 -4*2*-8)]/4
s = [15 +- sqrt(289)]/4
s = [15 +- 17]/4
Positive solution:
s = 8 mph (speed of the boat)
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Cheers,
Stan H.
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