------------------------------------------------------------------------------------ Start Time ------------------------------------------------------------------------------------ 6.00am
------------------------------------------------------------------------------------ Find LCM of 12, 30, 66 ------------------------------------------------------------------------------------ 12 = 2² x 3 30 = 2 x 3 x 5 66 = 2 x 3 x 11 LCM = 2² x 3 x 5 x 11 LCM = 660
⇒ The 3 lights will flash simultaneously again 660 sec later
------------------------------------------------------------------------------------ Convert seconds to minutes ------------------------------------------------------------------------------------ 660 sec = 11 min
------------------------------------------------------------------------------------ Calculate the next time the 3 lightships will flash simultaneously again ------------------------------------------------------------------------------------ 6.00 am + 11 mins = 6.11 am
------------------------------------------------------------------------------------ Answer: The 3 lightships will flash at 6.11 am again ------------------------------------------------------------------------------------