UPSC CAPF AC 2023 Paper

Suppose A, B and C are three taps fixed to the bottom of a tank with draining capacity 1 ∶ 2 ∶ 3. When all three of them are on, it takes 1 hour to drain out the full tank. If A and C are on but B is off, then how much time, in minutes, will it take to empty out a full tank of water?