SOLUTION: Debra's boat has a top speed of 6 miles per hour in still water. While traveling on a river at top speed, she went 10 miles upstream in the same amount of time she went 30 miles do
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Question 1053938: Debra's boat has a top speed of 6 miles per hour in still water. While traveling on a river at top speed, she went 10 miles upstream in the same amount of time she went 30 miles downstream. Find the rate of the river current. Answer by ikleyn(52788) (Show Source):
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Debra's boat has a top speed of 6 miles per hour in still water. While traveling on a river at top speed,
she went 10 miles upstream in the same amount of time she went 30 miles downstream. Find the rate of the river current.
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Your governing equation is "time" equation
= .
Here the left side is the time for travel 10 miles upstream at the speed (6-v) mph, where v is the current speed.
The right side is the time for travel 30 miles downstream at the speed (6+v) mph.
To solve the equation, multiply both sides by (6-v)*(6+v). You will get
10*(6+v) = 30*(6-v), or
60 + 10v = 180 -30v, or
40v = 120 ---> v = = 3.
Answer. The rate of the river current is 3 mph.
