How long will it take to fill the pool?

Three water pipes are used to fill a swimming pool. The first pipe alone takes 8 hours to fill the pool, the second pipe alone takes 12 hours to fill the pool, and the third pipe alone takes 24 hours to fill the pool. If all three pipes are opened at the same time, how long will it take to fill the pool?

MetroEye: This problem is similar to work-time problem. Refer MetroEye02

As per the formula,
\(\dfrac{1}{t} = \dfrac{1}{8} + \dfrac{1}{12}+ \dfrac{1}{24}= \dfrac{3 + 2 + 1}{24}  =  \dfrac{6}{24} =  \dfrac{1}{4}\)

=> t = 4

It will take 4 hours to fill the pool if all three pipes are opened at the same time.