SOLUTION: A small pipe can fill a tank in 8 min more time than it takes a larger pipe to fill the same tank. Working together, the pipes can fill the tank in 3 min. How long would it take ea

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: A small pipe can fill a tank in 8 min more time than it takes a larger pipe to fill the same tank. Working together, the pipes can fill the tank in 3 min. How long would it take ea      Log On

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Question 1073931: A small pipe can fill a tank in 8 min more time than it takes a larger pipe to fill the same tank. Working together, the pipes can fill the tank in 3 min. How long would it take each pipe, working alone, to fill the tank?
smaller pipe ......... min
larger pipe ......... min

Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
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Let x be the time for the large pipe to fill the tank working alone, in minutes.
Then the time for the small pipe to fill the tank working alone is (t+8) minutes.


The larger pipe fills 1%2Fx of the tank volume per minute.

The smaller pipe fills 1%2F%28x%2B8%29 of the tank volume per minute.

The two pipes fill 1%2Fx+%2B+1%2F%28x%2B8%29 of the tank volume, working simultaneously.

The condition says 

3%2Fx+%2B+3%2F%28x%2B8%29 = 1. 

--->  3*(x+8) + 3x = x*(x+8)  --->  x%5E2+%2B+2x+-+24 = 0  --->  (x-6)*(x+4) = 0  ---->

the only positive root is t= 6 minutes.


Answer.  6 minutes for the large pipe to fill the tank, and 6 + 8 = 14 minutes for the small pipe.

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For a wide variety of similar solved joint-work problems with detailed explanations see the lessons
    - Using Fractions to solve word problems on joint work
    - Solving more complicated word problems on joint work
    - Selected joint-work word problems from the archive
in this site.

Read them and get be trained in solving joint-work problems.

Also, you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this textbook under the topic "Rate of work and joint work problems" of the section "Word problems".