SOLUTION: A small pipe can fill an oil tank in 6 min more time than it takes a larger pipe to fill the same tank. Working together both pipes can fill a tank in 4 min. How long would it take

Algebra ->  Customizable Word Problem Solvers  -> Numbers -> SOLUTION: A small pipe can fill an oil tank in 6 min more time than it takes a larger pipe to fill the same tank. Working together both pipes can fill a tank in 4 min. How long would it take      Log On

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Question 437413: A small pipe can fill an oil tank in 6 min more time than it takes a larger pipe to fill the same tank. Working together both pipes can fill a tank in 4 min. How long would it take each pipe working alone to fill the tank?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let t = time for larger pipe to fill oil tank
given:
+t+%2B+6+ = time for smaller pipe to fill tank
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Add their rates of filling to get rate working together
+1%2Ft+%2B+1%2F%28t%2B6%29+=+1%2F4+
Multiply both sides by +4t%2A%28t%2B6%29+
+4%2A%28t+%2B+6%29+%2B+4t+=+t%2A%28t%2B6%29+
4t+%2B+24+%2B+4t+=+t%5E2+%2B+6t+
+t%5E2+-+2t+-+24+=+0+
+%28t-6%29%2A%28t%2B4%29+=+0+
The solutions are
t+=+-4 (can't use negative time)
t+=+6
and
+t+%2B+6+=+12
The smaller pipe takes 12 min
The larger pipe takes 6 min