Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively. In 30 minutes, how many times do they toll together?
(a) 4 (b) 10 (c) 15 (d) 16

• LCM of 2,4,6,8,10 and 12 is 12o
  i.e 120 sec = 2 min
  In 3o min [(30/2)+1] .....here 1 is added for last toll
  = 16
  ans:(d) 16
• 14 years agoHelpfull: Yes(25) No(4)
• L.C.M. of 2,4,6,8,10,12 is 120.
  So they toll once together in 2 minutes.
  In 30 minutes they toll together for 30/2 + 1 times= 16 times.
  Ans is (D)
• 14 years agoHelpfull: Yes(11) No(3)
• 16 considering first one at zero secs and 16th at 30 th min.
• 14 years agoHelpfull: Yes(9) No(1)
• 15 is the ans
• 10 years agoHelpfull: Yes(1) No(6)
• d
  lcm of 2,4,6,8,10,12
  +1
• 10 years agoHelpfull: Yes(0) No(0)
• 15 TIMES
  EVERY 120 SEC THEY TOLL TOGETHER
  
• 8 years agoHelpfull: Yes(0) No(1)