Three pipes, A, B, & C are attached to a tank. A & B can fill it
in 20 & 30 minutes respectively while C can empty it in 15 minutes.
If A, B & C are kept open successively for 1 minute each, how soon will the tank be filled?

• Three pipes, A, B, & C are attached to a tank. A & B can fill it in 20 & 30 minutes respectively while C can empty it in 15 minutes. If A, B & C are kept open successively for 1 minute each, how soon will the tank be filled?
  Ans: In one minute pipe A will fill = 1/20
  ⟹ In two minute pipe A and B will fill = 1/20 +1/30
  ⟹ In three minute pipe A, B and C will fill = 1/20 +1/30 - 1/15
  = 1/60
  ⟹ Let the number intervals of three minutes be x
  x/60 +1/20 +1/30 = 1
  x + 5 = 60
  x = 55
  ⟹ Time needed to fill the tank completely is = 55?3 + 2
  ( after 55 intervals of 3 minutes pipe A pipe B will take 1 minute each i.e 2 minutes) = 167 minutes.
  
• 11 years agoHelpfull: Yes(41) No(15)
• for 3 minutes, the part of the tank filled is (1/20)+(1/30)-(1/15)=(1/60)
  part filled in 165th minute is : 165/(3*60)=(55/60)
  166th minute: (55/60)+(1/20)=(58/60)
  167th minute: (58/60)+(1/30)=(60/60)
  hence the solution is 167th minute
• 11 years agoHelpfull: Yes(14) No(30)
• For Every 3 minutes volume of water filled --- 1/20 + 1/30 -1/15 = 1/60
  
  So for 3 minutes 1 part will be filled out of 60 parts.
  
  Total to Fill full tank is 3 * 60 = 180 mins = 3hours
• 7 years agoHelpfull: Yes(5) No(9)
• x/60 +1/20 +1/30 = 1
  x + 5 = 60
  x = 55
  than 55*3+2=167
  because it takes 55 minutes
• 9 years agoHelpfull: Yes(1) No(7)
• In three minute pipe A, B and C will fill = 1/20 +1/30 - 1/15 = 1/60
  
  So, x/60 +1/20 +1/30 = 1
  x = 55
  
  Hence, Time needed to fill the tank completely is = 55*3 + 2 = 167th minutes.
• 7 years agoHelpfull: Yes(1) No(1)