SOLUTION: An oil tank at a refinery has two inlet pipes and one outlet pipe. One inlet pipe can fill the tank in 6h, and the other inlet pipe can fill the tank in 12h. The outlet pipe can em

Algebra ->  Rate-of-work-word-problems -> SOLUTION: An oil tank at a refinery has two inlet pipes and one outlet pipe. One inlet pipe can fill the tank in 6h, and the other inlet pipe can fill the tank in 12h. The outlet pipe can em      Log On


   

Question 171652: An oil tank at a refinery has two inlet pipes and one outlet pipe. One inlet pipe can fill the tank in 6h, and the other inlet pipe can fill the tank in 12h. The outlet pipe can empty the tank in 24h. How long would it take to fill the tank with all three pipes open?
Please, hep me with this problem, i'm trying since friday to solve it =( Tank you
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
An oil tank at a refinery has two inlet pipes and one outlet pipe. One inlet pipe can fill the tank in 6h, and the other inlet pipe can fill the tank in 12h. The outlet pipe can empty the tank in 24h. How long would it take to fill the tank with all three pipes open?
:
Let the full tank = 1; + for filling, - for draining
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Let t = time required when all three pipes are open:
t%2F6 + t%2F12 - t%2F24 = 1
Multiply equation by 24 to get rid of the denominators, results:
4t + 2t - t = 24
:
5t = 24
t = 24%2F5
t = 4.8 hrs to fill when all pipes are open
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Check solution using a calc:
4.8%2F6 + 4.8%2F12 - 4.8%2F24
.8 + .4 - .2 = 1
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:
Not that hard, right?