Answer:
2 hours
Step-by-step explanation:
Rate and TIme are inverse of each other.
First, lets find rates of each.
Pump A:
takes 6 hours to fill up so rate is 1/6
Pump B:
takes 3 hours to fill up so rate is 1/3
Combined rates of Pump A and Pump B:
1/6 + 1/3
The time it takes to fill up if BOTH turned on together would be the COMBINED RATE's INVERSE. Shown below the calculation:
[tex](\frac{1}{6}+\frac{1}{3})^{-1}\\=(\frac{1}{6}+\frac{2}{6})^{-1}\\=(\frac{1}{2})^{-1}\\=2[/tex]
So, it takes 2 hours
