Two pipes A and B can fill a tank in 24 minutes and 32 minutes respectively. If both the pipes are
opened simultaneously, after how much time should B be closed so that the tank is full in 18
minutes?

• pipe A will work for 18 minutes. suppose pipe B is closed after x minutes than
  we have 18/24+x/32=1
  x=8 minute.
• 13 years agoHelpfull: Yes(60) No(9)
• let B be closed after X minutes.
  part filled by (A+B) in X min + Part filled by A in (18-X) min =1
  x( 1/24 +1/32)+ (18-x)1/24=1
  x=8
  hence, B must be closed after 8 minutes.
• 9 years agoHelpfull: Yes(5) No(0)
• A=1/24
  B=1/32
  let after t time B is closed so..
  A+tB=1/18
  1/24+t/32=1/18
  t=5/9mint=4*60/9=80/3 sec=27 sec
  so after 27 second pipe shoul be closed ...
  
• 13 years agoHelpfull: Yes(3) No(36)
• Let the time for which the pipes A & B work together be 'x' and the time for which the pipe A works alone after the pipe B is closed be 'y'.
  So, x(1/24 + 1/32) + y(1/24)=1 - Equation (1)
  and x + y = 18 - Equation (2)
  Solving Equation (1) we get,7x+4y=96
  x = 18 - y (from Equation (2)),
  Putting this value of x in Equation (1) we get, 7(18 - y) + 4y = 96 simplifying it we get 126-7y+4y=96 further simplifying it we get the value of y as 10 and x as 8. It means that pipes A & B works together for 8 minutes and after 8 minutes pipe B should be closed so that the remaining part of the tank is filled by pipe A in 10 minutes.
• 10 years agoHelpfull: Yes(3) No(0)
• 18/24+x/32=1
  x=8 minute.
• 9 years agoHelpfull: Yes(1) No(0)
• A will full a part of tank in 24 min, ie. in 18 min its will fill (18/24) = 3/4 part...
  that means 1/4 part is to be filled by B
  
  in 32 minutes b will full a tank.. so in 8 minutes B will fill (1/4) of the part...
• 9 years agoHelpfull: Yes(1) No(2)
• A and B fill for x mins.
  A alone fills for (18-x) mins.
  so x/24+x/32+(18-x)/24=1
  solve this will get 8 mins.
  
• 9 years agoHelpfull: Yes(1) No(0)
• let after x mins pipe B is closed.
  hence by equation,
  (both pipes work for x mins)+(pipe A works for 18-x mins)=1
  x(1/24+1/32) + (18-x)(1/24)=1
• 9 years agoHelpfull: Yes(0) No(0)
• let x=24,y=32,t=18
  required time=y(1-t/x)
  =32(1-18/24)
  =8 min
• 7 years agoHelpfull: Yes(0) No(0)