SOLUTION: Mr. Turner has a motorboat that can travel 14 mph in still water. He wishes to take a trip on a river whose current flows at the rate of 2 mph. If he has 7 hours at his disposal, h

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Mr. Turner has a motorboat that can travel 14 mph in still water. He wishes to take a trip on a river whose current flows at the rate of 2 mph. If he has 7 hours at his disposal, h      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 162351: Mr. Turner has a motorboat that can travel 14 mph in still water. He wishes to take a trip on a river whose current flows at the rate of 2 mph. If he has 7 hours at his disposal, how many hours should he spend on the first part of his trip going downstream before returning upstream to his starting point?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Mr. Turner has a motorboat that can travel 14 mph in still water.
He wishes to take a trip on a river whose current flows at the rate of 2 mph.
If he has 7 hours at his disposal, how many hours should he spend on the first
part of his trip going downstream before returning upstream to his starting point?
:
Let t = time going down-stream
then
(7-t) = time going up-stream
:
14 + 2 = 16 mph; boat speed down-stream
14 - 2 - 12 mph; boat speed up-stream
:
Distance both ways are the same, write a dist equation: dist = speed * time
:
Dist down = dist up
16t = 12(7-t)
:
16t = 84 - 12t
:
16t + 12t = 84
:
28t = 84
t = 84%2F28
t = 3 hrs he can travel down-stream, before he has 4 hrs to return
:
:
confirm solution by finding the distances down and back:
16*3 = 48 mi
12*4 = 48 mi