There are 3 pipes A, B and C that when opened simultaneously would fill a tank in 20 minutes. C can fill the tank
twice as fast as A which in turn would fill the tank twice as fast as B. How long will it take for B alone to
fill the tank?

• If b is the time ( in minutes) taken by pipe B to fill the tank.
  Then 1/b tank is filled by B in 1 minute
  
  2/b tank is filled by A in 1 min
  4/b tank is filled by c in 1 min.
  
  1/b + 2/b+ 4/b tank is filled by 3 pipes in 1 min.
  
  as per given condition,
  
  1/b + 2/b+ 4/b = 1/20
  7/b = 1/20
  b=140
  
  so pipe B alone can fill tank in 140 hrs.
  
• 12 years agoHelpfull: Yes(0) No(0)