SOLUTION: If a boat can travel 30mph in still water, and can travel 9 miles downstram in the same time it takes 1 mile to go upstream, what is the rate of the rivers current?

Question 795399: If a boat can travel 30mph in still water, and can travel 9 miles downstram in the same time it takes 1 mile to go upstream, what is the rate of the rivers current?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = the rate of the current in mi/hr
= boat's speed going downstream in mi/hr
= boat's speed going upstream in mi/hr
Let = the time in hours for both upstream and downstream
-----------------------
Equation for going downstream:
(1)
Equation for going upstream:
(2)
--------------------
(1)
and
(2)
-------------------
Add the equations

and
(1)
(1)
(1)
The rate of the current is 24 mi/hr
check:
(2)
(2)
(2)
and
(1)
(1)
(1)
OK

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