Pipe A can fill a tank in 12 minutes whereas pipe A along with pipe B can fill the same tank in 8 minutes. In what time pipe B alone can fill the tank?

24 min

Let the capacity of the tank be 1 unit.

• Pipe A fills the tank in 12 minutes.

So, A's filling rate is: $\frac{1}{12}$

• Pipe A + Pipe B fill the tank in 8 minutes.

Their combined filling rate is: $\frac{1}{8}$

Therefore, Pipe B's filling rate is:

$\frac{1}{8} - \frac{1}{12} = \frac{3 - 2}{24} = \frac{1}{24}$

Hence, Pipe B alone will fill the tank in: $24\text{ minutes}$