Respuesta :
Given:
A new type of pump can drain a certain pool in 9 hours.
An older pump can drain the pool in 11 hours.
To find:
The required time when both pumps work together to drain the pool.
Explanation:
One hour's work of the new pipe is,
[tex]\frac{1}{9}[/tex]One hour's work of the old pipe is,
[tex]\frac{1}{11}[/tex]So, one hour's work of both the pipe together is,
[tex]\begin{gathered} \frac{1}{9}+\frac{1}{11}=\frac{11+9}{9(11)} \\ =\frac{20}{99} \end{gathered}[/tex]Therefore, the time taken to drain the pool for both the pipes together is,
[tex]\begin{gathered} \frac{99}{20}hours \\ (or) \\ 4\text{ }hours\text{ 57minutes} \end{gathered}[/tex]Final answer:
The required time to drain the pool for both the pipes together is 4 hours 57 minutes.
