It is a typical Tap problem. There are two taps, which are used to fill the tank and one tap to empty the tank. First tap fill the tank in 10 min., while the second takes quarter of an hour to fill the tank if both are operated independently. Third tap is capable of emptying the tank in seven and a half minutes. If all the taps are opened simultaneously (when the tank is empty) how long (if ever) will it take for the tank to get filled completely?

• 30 mins..
  
  in 1min
  1st tap fills 1/10th of tank
  2nd tap fills 1/15th of tank
  
  mean while 3rd tap empties 1/7.5th of tank
  
  so.. in 1min [(1/10)+(1/15)-(1/7.5)]th tank is filled i.e.. 1/30th tank is filled
  
  1min - (1/3o)th tank filled....
  ? - 1
  so ans= 30 mins....
  
  
• 10 years agoHelpfull: Yes(3) No(0)
• CONSIDER 3 TAPS A,B,C
  A fill in 10 mins,b fill it in 15 min, c empty it in 15/2 min.
  total time to fill= 1/10+1/15-2/15=1/30=30 min
• 10 years agoHelpfull: Yes(1) No(0)
• 30 mins :)
• 10 years agoHelpfull: Yes(0) No(0)