# Thread: Pipe Filling

1. ## Pipe Filling

Hi,

I have 3 Pipes. First pipe can fill a tank in 10 minutes, second pipe can fill the tank in 15 minutes and 3rd pipe can fill the tank in 20 minutes. What formula can I apply to calculate the time to fill the tank, if all the three pipes are opened simultaneously?

Where can I get more information on this?

Thanks!

2. Originally Posted by ManuLi Hi,

I have 3 Pipes. First pipe can fill a tank in 10 minutes, second pipe can fill the tank in 15 minutes and 3rd pipe can fill the tank in 20 minutes. What formula can I apply to calculate the time to fill the tank, if all the three pipes are opened simultaneously?

Where can I get more information on this?

Thanks!
Hi ManuLi,

Pipe 1 fills $\displaystyle \frac{1}{10}$ of the tank in 1 minute.
Pipe 2 fills $\displaystyle \frac{1}{15}$ of the tank in 1 minute.
Pipe 3 fills $\displaystyle \frac{1}{20}$ of the tank in 1 minute.

$\displaystyle \frac{1}{10}+\frac{1}{15}+\frac{1}{20}=\frac{1}{t}$

Solve for $\displaystyle t$

For more information, you might look here: "Work" Word Problems

3. For "work" problems like this, whether it is people working or pipes filling a tank, rates or work add.

"First pipe can fill a tank in 10 minutes" means it fills 1/10 tank per minute. "Second pipe can fill the tank in 15 minutes" means it fills1/15 tank per minute and "3rd pipe can fill the tank in 20 minutes" means it fills 1/10 tank per minute.

Add those, as masters shows, to find the rate at which all three, together, will fill the tank. Once you have that in "tanks per minute" (what masters calls "1/t") the time to file one tank, "minutes per tank" is the reciprocal.

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