SOLUTION: A boat can travel on a river 7 miles upstream in the same time it takes to travel 19 miles downstream. Find the current speed if the speed of the boat is 8 miles per hour in still
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Question 517658: A boat can travel on a river 7 miles upstream in the same time it takes to travel 19 miles downstream. Find the current speed if the speed of the boat is 8 miles per hour in still water Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! A boat can travel on a river 7 miles upstream in the same time it takes to travel 19 miles downstream.
Find the current speed if the speed of the boat is 8 miles per hour in still water
:
Let c = speed of the current
then
(8+c) = effective speed downstream
and
(8-c) = effective speed upstream
:
Write a time equation, time = dist/speed
:
Time up = time down =
cross multiply
7(8+c) = 19(8-c)
56 + 7c = 152 - 19c
7c + 19c = 152 - 56
26c = 96
c = 96/26
c ~ 3.69 mph
:
:
Check this by finding the times, they should be equal, if we did it right.
7/(8-3.69) = 1.62 hrs
19/(8+3.69) = 1.62 hrs
