SOLUTION: Junior’s boat will go 15 miles per hour in still water. If he can go 12 miles downstream in the same amount of time as it takes to go 9miles upstream then what is the speed of the

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Junior’s boat will go 15 miles per hour in still water. If he can go 12 miles downstream in the same amount of time as it takes to go 9miles upstream then what is the speed of the      Log On


   

Question 192008This question is from textbook Elementary and intermediate algebra
: Junior’s boat will go 15 miles per hour in still water. If he can go 12 miles downstream in the same amount of time as it takes to go 9miles upstream then what is the speed of the current This question is from textbook Elementary and intermediate algebra

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Junior’s boat will go 15 miles per hour in still water. If he can go 12 miles
downstream in the same amount of time as it takes to go 9 miles upstream then
what is the speed of the current.
:
Let c = speed of the current
:
(15+c) = speed downstream
and
(15-c) = speed upstream
:
Write a time equation; Time = distance%2Fspeed
Time down = time up
12%2F%28%2815%2Bc%29%29 = 9%2F%28%2815-c%29%29
Cross multiply
9(15+c) = 12(15-c)
135 + 9c = 180 - 12c
9c + 12c = 180 - 135
21c = 45
c = 2.143 mph is the speed of the current
:
:
Check solution by finding the times using a calc:
12%2F%28%2815%2B2.143%29%29 = 7.0
9%2F%28%2815-2.143%29%29 = 7.0 hrs