SOLUTION: It takes pipe B 5 hours longer to drain a tank than pipe A. If both pipes are open it take 6 hours to drain the tank. How long does it take for Pipe A working alone to drain the ta

Algebra ->  Rate-of-work-word-problems -> SOLUTION: It takes pipe B 5 hours longer to drain a tank than pipe A. If both pipes are open it take 6 hours to drain the tank. How long does it take for Pipe A working alone to drain the ta      Log On


   



Question 245715: It takes pipe B 5 hours longer to drain a tank than pipe A. If both pipes are open it take 6 hours to drain the tank. How long does it take for Pipe A working alone to drain the tank?
Answer by marcsam823(57) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = # hours it takes Pipe A to drain the tank working alone
Let x + 5 = # hours it takes Pipe B to drain the tank working alone
Let 1/x = portion of the job Pipe A can perform in one hour
Let 1/(x+5)= portion of the job Pipe B can perform in one hour

Set up the equation:
Here it is in words:
(portion of the job Pipe A can perform in one hour + portion of the job Pipe B can perform in one hour) x # hours to perform the job = 100% of the job or 1 job completed

And Algebraically:
Solve for x:
(1/x + 1(x+5))(6) = 1
%28%28x%2B5%29%2F%28%28x%29%28x%2B5%29%29+%2B+x%2F%28%28x%29%28x%2B5%29%29%29%286%29+=+1
%282x%2B5%2F%28x%5E2+%2B5x%29%29%286%29+=+1
%2812x+%2B+30%29%2F%28x%5E2+%2B+5x%29+=+1
12x+%2B+30+=+x%5E2+%2B+5x%7D%7D%5D%0D%0A%7B%7B%7Bx%5E2+-+7x+-+30+=+0
%28x+-+10%29%28x+%2B+3%29+=+0
x+=+10
x = -3 Reject this answer (cannot have a negative value for time)
It takes Pipe A 10 hours to drain the tank working alone