Answer:
20 hour
Step-by-step explanation:
Let the total capacity of the pool is 100%
It is given that 2/3 of the pool is already filled means [tex]100\times \frac{2}{3}=66.66[/tex] % is already filled
So 100%-66.66%= 33.33 % pipe is empty
it is given that it takes 12 hours to fill the pool so inlet rate is [tex]\frac{1}{12}[/tex]
It is also given that it can empty in 15 hours so outlet rate is [tex]\frac{1}{15}[/tex] So equivalent rate for filling the pool is [tex](\frac{1}{12}-\frac{1}{15})\times 100=1.666[/tex] %
So time required to fill the pool is [tex]=\frac{33.33}{1.666}=20[/tex] hour
