SOLUTION: it took 20 min to go up stream. 15 to come back. the speed off the current is 5 mph.What is the speed of the boat? The speed of the boat is 35 MPH. how to you get to that answ

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Question 485629: it took 20 min to go up stream. 15 to come back. the speed off the current is 5 mph.What is the speed of the boat?

The speed of the boat is 35 MPH. how to you get to that answer?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
it took 20 min to go up stream. 15 to come back. the speed off the current is 5 mph.
What is the speed of the boat?
:
We are dealing with mph therefore:
Change 20 min to 1%2F3 hr
Change 15 min to 1%2F4 hr
:
let s = speed of boat in still water
then
(s-5) = effective speed up stream
and
(s+5) = effective speed down stream
:
Write a dist equation; dist = speed * time
:
up dist = down dist
1%2F3(s-5) = 1%2F4(s+5)
multiply by 12 to get rid of those fractions, results
4(s-5) = 3(s+5)
4s - 20 = 3s + 15
4s - 3s = 15 + 20
s = 35 mph speed of boat in still water