Two taps can fill a tank in 12 and 18 min. respectively . Both are kept open for 2 min. and the first is turned off. In how many min. more will the tank be filled?
[A] 18 min
[C] 16 min
[B] 11 min
[D] 13 min

• Tank filled in 2 mins= 2*(1/12 +1/18) = 2*5/36 = 5/18
  remaining tank to be filled by 2nd tap = 13/18
  5/6 tank will be filled by 2nd tank in (13/18)*18= 13 mins .... option D
• 12 years agoHelpfull: Yes(33) No(5)
• in 2 min A&B fill = 2(1/12 + 1/18) = 5/18 tank
  only B fill 1 - 5/18 = 13/18 tank
  B 1 min fill 1/18 tank
  13/18 tank = 13 min
  
• 9 years agoHelpfull: Yes(4) No(2)
• Take LCM IS
  a->12
  b->18
  take LCM for both is 36
  then 36/12=3 & 36/18=2 so, total is 5 min
  working of two pipes for 2min is (a+b)2+b=36
  (3+2)2+b=36
  b=26 => 26/2=13hr
• 10 years agoHelpfull: Yes(3) No(3)