SOLUTION: solve. Round to the nearest tenth of necessary Donna and Evan canoed a total of 14 mi upstream and back. The round trip took 8 hrs. If they row at a rate of 4 mi/hr in still w

Question 1034410: solve. Round to the nearest tenth of necessary

Donna and Evan canoed a total of 14 mi upstream and back. The round trip took 8 hrs. If they row at a rate of 4 mi/hr in still water, how fast was the current?
Answer by jorel555(1290) (Show Source): You can put this solution on YOUR website!
Let's use r as our rate of the current; Assuming they canoed 14/2, or 7 miles each way, then:
(7 miles/4+rmph)+(7 miles/4-rmph)=8
7(4+r)+7(4-r)=8(16-r^2)
28+7r+28-76=128-8r^2
8r^2=72
r^2=9
r=3
The rate of the river is 3 mph!!!!!!!!

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