It takes 7.2 hours for the two pipes to fill the pool if they operate simultaneously
Solution:
Given that,
A pipe can fill a pool in 12 hours
Thus, in one hour first pipe does [tex]\frac{1}{12}[/tex] of the job
Another pipe can fill the pool in 18 hours
Thus, in one hour second pipe does [tex]\frac{1}{18}[/tex] of the job
Therefore, we can say,
In "x" hours, first pipe does [tex]\frac{x}{12}[/tex] of the job
In "x" hours, second pipe does [tex]\frac{x}{18}[/tex] of the job
Working together they do the one job.
Thus, we get,
[tex]\frac{x}{12} + \frac{x}{18} = 1\\\\x(\frac{1}{12} + \frac{1}{18}) = 1\\\\x(\frac{12+18}{12 \times 18}) = 1\\\\x(\frac{30}{216}) = 1\\\\x = \frac{216}{30}\\\\x = 7.2[/tex]
Thus, it takes 7.2 hours for the two pipes to fill the pool if they operate simultaneously
