an empty tank is filled with an inlet pipe A in 42 min.after 12 min an outlet pipe B is opened which can empty the the tank in 30 min. after 6 min another inlet pipe C opened into the same tank,which can fill the tank in 35 min and tank is filled find the time taken

• Rate at which A fill is 1/42 per min
  
  A filled for 12 min so tank filled by A will be 12/42
  
  Similarly B empty the tank for 6 min
  
  now the volume will be (18/42) -(6/30) = 8/35 because at the 6 min A has also filled.
  
  Now the amount left to be filled is (1-8/35) = 27/35
  
  Now C comes it fills 1/35 per minute.
  
  So from now the amount will be filled is (1/42+1/35-1/30) = 2/105 per minute
  
  So to fill the required amount it will take 105/2 * 27/35 = 40.5 min
  
  So total time is 12+6+40.5 = 58.5 min
• 11 years agoHelpfull: Yes(38) No(1)
• 58.5 mins.
  (18+x)/42 + x/35 - (6+x)/30 = 1
  x = 40.5
  time = 40.5+18 = 58.5 mins
• 12 years agoHelpfull: Yes(36) No(9)
• let the tank be filled in t minutes after opening tap C
  now total part of tank filled=[(t/42)-(t/30)+(t/35)]
  now
  (12/42)-(6/30)+(6/42)+[(t/42)-(t/30)+(t/35)=1
  solve for t we get t=40.5 minutes
  therefore
  total time= 40.5min + 12min(when A was opened) + 6 min(when B was opened)= 58.5 min ans.
  
  
  
• 9 years agoHelpfull: Yes(7) No(0)
• for first 18 min a and b fills the tank so, 18/42-6/30=8/35
  when c is opened a,b and c will fills remaining 27/35 part, so
  (1/42+1/35-1/30)=2/105
  for 27/35 part, 105/2*27/35=40.5 min
  so first 18 min+40.5 min=58.5 min
• 9 years agoHelpfull: Yes(5) No(0)
• 40.5 mins in total
  
• 12 years agoHelpfull: Yes(4) No(14)
• (6/21)-(1/5)+t/35=1
  i thnk ans is 32 min
  
• 12 years agoHelpfull: Yes(4) No(9)
• 56.5 min in totl
  
• 12 years agoHelpfull: Yes(2) No(6)
• 12(1/42)-6(1/30)+X(1/35)=1
  solving this we get X=18 soo total 18+12+6=36min
  soo it takes 36 min to fill the tank..... i m nt sure can any1 tell e wheather i m correct?? if nt post ans plz let me knw
• 12 years agoHelpfull: Yes(2) No(8)
• Let x be the total time
  (x/42) - (x-12)/30 - (x-18)/35=1
• 9 years agoHelpfull: Yes(2) No(0)
• Assume total tank capacity = 210 Liters
  Now capacity of pipe A = 210/42 = 5 Liters
  Capacity of B = 210 / 30 = - 7 Liters
  Capacity of C = 210 / 35 = 6 min
  Assume tank gets filled in x min after the third pipe got opened.
  So x×5+6×(−2)+4x=210x×5+6×(−2)+4x=210
  ⇒48+4x=210⇒4x=162⇒x=40.5⇒48+4x=210⇒4x=162⇒x=40.5
  Total time taken to fill the tank = 40.5 + 12 + 6 = 58.5
• 8 years agoHelpfull: Yes(1) No(0)
• i got 58.5 mins
• 9 years agoHelpfull: Yes(0) No(1)
• 57 mins.
  (18+x)/42 + x/35 - (6+x)/30 = 1
  x = 39
  time = 39+18 = 57 mins
  Read more at http://www.m4maths.com/frequently-asked-placement-questions.php?SOURCE=TCS#vfVsWwmQ0MoDKsWp.99
• 9 years agoHelpfull: Yes(0) No(1)
• cant be filled
  
• 9 years agoHelpfull: Yes(0) No(2)
• A fill the tank in 1 min = 1/42
  6 min =6/42 =2/7
  work left after 12 min = 1-2/7 = 5/7
  
  
• 9 years agoHelpfull: Yes(0) No(1)
• Assume total tank capacity = 210 Liters
  Now capacity of pipe A = 210/42 = 5 Liters
  Capacity of B = 210 / 30 = - 7 Liters
  Capacity of C = 210 / 35 = 6 min
  Assume tank gets filled in x min after the third pipe got opened.
  So
  x
  ×
  5
  +
  6
  ×
  (
  −
  2
  )
  +
  4
  x
  =
  210
  
  ⇒
  48
  +
  4
  x
  =
  210
  ⇒
  4
  x
  =
  162
  ⇒
  x
  =
  40.5
  
  Total time taken to fill the tank = 40.5 + 12 + 6 = 51.5
• 6 years agoHelpfull: Yes(0) No(0)
• take lcm of 42 ,30, 35 get 210 as a lcm so assume 210 liter as a tank capacity
  
  so a gives 5 liter per minute , b removes 7 liter per minute ,c gives 6 liter per minute
  
  so first 18 minutes a fills 18 * 5 = 90 liters and b removes 6*7 =42 liters so net =48 liters
  
  remain 162 liters abc together per minute fill 4 liter (6-7+5=4)
  
  so 162/4 = 40.5 minutes
  
  al ready take 18 minutes add all we got 58.5 minutes
• 5 years agoHelpfull: Yes(0) No(0)
• Assume total tank capacity = 210 Liters
  Now capacity of pipe A = 210/42 = 5 Liters
  Capacity of B = 210 / 30 = - 7 Liters
  Capacity of C = 210 / 35 = 6 min
  Assume tank gets filled in x min after the third pipe got opened.
  So
  x
  ×
  5
  +
  6
  ×
  (
  −
  2
  )
  +
  4
  x
  =
  210
  
  ⇒
  48
  +
  4
  x
  =
  210
  ⇒
  4
  x
  =
  162
  ⇒
  x
  =
  40.5
  
  Total time taken to fill the tank = 40.5 + 12 + 6 = 51.5
• 5 years agoHelpfull: Yes(0) No(0)