SOLUTION: Jan and Tariq took a canoeing trip, traveling 6 mi upstream against a 2-mi/h current. They then returned to the same point downstream. If their entire trip took 4 hr, how fast coul

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Question 964015: Jan and Tariq took a canoeing trip, traveling 6 mi upstream against a 2-mi/h current. They then returned to the same point downstream. If their entire trip took 4 hr, how fast could they paddle in still water?
Answer by LinnW(1048)   (Show Source): You can put this solution on YOUR website!
Use the formula, rate * time = distance
Set x = speed in still water
(x-2) * t1 = 6 miles
(x+2) * t2 = 6 miles
t1, the time paddling upstream = distance 6 miles/ rate (x-2) or
6/(x-2)
t2, the time paddling downstream = distance 6 miles/ rate (x+2) or
6/(x+2)
t1 + t2 = 4 hours, so
6/(x-2) + 6/(x+2) = 4
A common denominator is (x-2)(x+2) so we want

expanding

simplify

do cross products



divide by 4

factoring

So possible values for x are 4 and -1
Since we need a positive speed, the speed in
still water is 4 mph

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