SOLUTION: a pipe can fill a vat in 8 hours. a second pipe can fill the vat in 4 hours. if a third is added, the vat is filled in 2 hours. how long would it take for the third pipe to fill th

Algebra ->  Rate-of-work-word-problems -> SOLUTION: a pipe can fill a vat in 8 hours. a second pipe can fill the vat in 4 hours. if a third is added, the vat is filled in 2 hours. how long would it take for the third pipe to fill th      Log On


   



Question 763106: a pipe can fill a vat in 8 hours. a second pipe can fill the vat in 4 hours. if a third is added, the vat is filled in 2 hours. how long would it take for the third pipe to fill the vat?
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
The rates of all the three pipes are additive when they are working together. Use the rates in the unit arrangement of "fill the vat" per hour. Call this "fill the vat", one job.

You then can use the uniform rates property, rate*time=jobs. If u is the rate of filling for the third pipe, then you have the equation:
highlight%281%2F8%2B1%2F4%2B1%2Fu=1%2F2%29
Just solve for u.