Three wheels make 36, 24, 60 rev/min. Each has a black mark on it. It is aligned at the start of the qn. When does it align again for the first tym? please explain

• 5 seconds
  Let after 'x' mins, the three wheels again come to their original positions
  -->
  The number of revolutions completed by the wheels would be respectively 36x, 24x, 60x
  --->
  
  Now 'x' should be minimum rational number such that 36x, 24x, 60x all becomes integral because their being integral means that the wheel has come to its original positions or 'x' will be the reciprocal of the HIGHEST COMMON FACTOR of all these many revolutions
  -->
  
  x = 1/12 minutes or 5 seconds--> The wheels will complete respectively 3,2 & 5 revolutions.
• 14 years agoHelpfull: Yes(41) No(5)
• It will come back after 360 mins.
  LCM of 36, 24 and 60.
• 14 years agoHelpfull: Yes(11) No(36)
• G.C.M.of 36,24,60 is 360 hence after 360 revolutions it will align for first time. but time for 1 st wheel is 10 min. for 2 nd 15 min for 3 rd wheel 6 min. to complete 360 revolutions.
• 14 years agoHelpfull: Yes(7) No(14)
• 36/60, 24/60, 60/60
  3/5, 2/5, 1
  
  distance each "black mark" moves:
  (3/5)t, (2/5)t, t rev
  
  The first time these would all be integers (after t = 0) again occurs when t = 5 s.
  
• 8 years agoHelpfull: Yes(0) No(1)
• rev/sec:
  36/60, 24/60, 60/60
  3/5, 2/5, 1
  
  distance each "black mark" moves:
  (3/5)t, (2/5)t, t rev
  
  The first time these would all be integers (after t = 0) again occurs when t = 5 s.
• 7 years agoHelpfull: Yes(0) No(0)