SOLUTION: It takes a motorboat 4 hours to travel 56 miles down a river, and 3 hours longer to make the return trip. Find the speed of the river current.

Question 131478This question is from textbook
: It takes a motorboat 4 hours to travel 56 miles down a river, and 3 hours longer to make the return trip. Find the speed of the river current. This question is from textbook

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
It takes a motorboat 4 hours to travel 56 miles down a river, and 3 hours longer to make the return trip. Find the speed of the river current.
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Downstream DATA:
Time = 4 hr ; distance = 56 miles ; rate = d/t = 56/4 = 14 mph
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Upstream DATA:
Time = 7 hr ; distance = 56 miles ; rate = d/t = 56/7 = 8 mph
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Let boat speed be "b"; Let water speed be "w"
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EQUATIONS:
b+w = 14
b-w = 8
Add to get:
2b = 22
b = 11 mph (boat speed in still water)
Substitute to get water speed:
11+w = 14
w = 3 mph (water speed)
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Cheers,
Stan H.
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