Three taps A, B, C can fill an overhead tank in 4, 6 and

Three taps A, B, C can fill an overhead tank in 4, 6 and 12 hours respectively. How long would the three taps take to fill the tank if all of them are opened together ?

On the basis of given details in question ,

Part of the tank filled by all three taps in an hour =	1	+	1	+	1	=	6 + 4 + 2	=	1
	4		6		12		24		2

∴ Hence, the tank will be filled in 2 hours.