Three taps A, B and C can fill an overhead tank in 6 hours, 8 hours and 12 hours respectively. How long would the three taps take to fill the empty tank, if all of them are opened together?
Number of hours tap A requires to fill the tank : 6
Number of hours tap B requires to fill the tank : 8
Number of hours tap C requires to fill the tank : 12
Amount of water filled by tap A in one hour: 
Amount of water filled by tap B in one hour: 
Amount of water filled by tap C in one hour: 
Amount of water filled by taps A, B and C together in one hour: 
= 
= 
They can fill the tank together in 
hours = 
hours = 2 hours 40 min.
17