Three taps A, B and C together can fill a tank in 6 h. After working 2 h, C is closed and the tank was filled in 8 h more. Find the time in which C alone can fill the tank?

Work of (A + B + C) in 1 H = 1 / 6
Work done in 2 h = 2/6 = 1/3
Remaining part of the tank = 1 - 1/3 = 2/3
Time taken by A + B to fill this 2/3rd part of the tank = 8 h
A and B together can fill tank in 12 h (i.e., 8 x 3/2).
Now, we have A, B and C together filling the tank in 6 h and A and B together fill tank in 12 h.
Work done by C alone in 1 h = 1/6 - 1/12 = 1/12
Hence, C alone can fill the tank in 12 h.