SOLUTION: A boat travels 18 mph in still water can travel 22 miles downstream in the same time as it takes to travel. 14 miles upstream. Find the speed of the current river.

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Question 810814: A boat travels 18 mph in still water can travel 22 miles downstream in the same time as it takes to travel. 14 miles upstream. Find the speed of the current river.
Found 2 solutions by erica65404, stanbon:
Answer by erica65404(394) (Show Source):
You can put this solution on YOUR website!
to find the rate of the water you need to use the speed of the boat.
distance/rate
we are going to put downstream on one side and upstream on the other.
the distance for downstream is 22 miles. the rate is going to be 18 + x. The reason for this is because when you are going down a river, the river pushes you along and increases your speed. The overall speed is going to be more than 18.

The distance for going upstream is 14. The rate is going to be 18 - x. The river pushes against the boat causing the boat to slow down. so the overall speed is going to be less than 18mph.

now make them equal to each other.

cross multiply and solve for x.

the current of the water is 4mph.

Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
A boat travels 18 mph in still water can travel 22 miles downstream in the same time as it takes to travel. 14 miles upstream. Find the speed of the current river.
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Downstream DATA:
rate = 18 + c mph ; distance = 22 miles ; time = 22/(18+c) hrs
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Upstream DATA:
distance = 14 miles ; rate 18-c mph ; time = 14/(18-c) hrs
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Equation:
22/(18+c) = 14/(18-c)
11(18-c) = 7(18+c)
198 - 11c = 126 + 7c
18c = 72
c = 4 mph (speed of the current)
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Cheers,
Stan H.
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