SOLUTION: The rate of a boat in still water is 7km/hr. If the boat can travel 30km downstream in the same time it can travel 12 km upstream, find the rate of the river current.
Is there a
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Question 1011286: The rate of a boat in still water is 7km/hr. If the boat can travel 30km downstream in the same time it can travel 12 km upstream, find the rate of the river current.
Is there a formula for this kind of question? Please help!
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
It's not really a "formula"
It's just catching on to a method
Just use [ distance ] = [ rate ] x [ time ]
--------------------------
Let = the rate of the current in km/hr
= rate of the boat going downstream
= rate of the boat going upstream
Let = time in hrs for going either upstream or downstream
------------------------------------
Equation for going downstream:
(1)
Equation for going upstream:
(2)
----------------------------
(1)
Substitute this into (2)
(2)
Multiply both sides by
(2)
(2)
(2)
(2)
The rate of the current is 3 km/hr
-----------------------------
check:
(1)
(1)
(1)
(1)
and
(2)
(2)
(2)
(2)
OK
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