The Royal Hawaiian Hotel decorates its Rainbow Christmas Tree with non-flashing white lights and a series of colored flashing lights - red, blue, green, orange, and yellow. The red lights turn red every 20 seconds, the blue lights turn blue every 30 seconds, the green lights turn green every 45 seconds, the orange lights turn orange every 60 seconds, and yellow lights turn yellow every 1 minute and 20 seconds. The manager plugs the tree in for the first time on December 1st precisely at midnight and all lights begin their cycle at exactly the same time. If the five colored lights flash simultaneously at midnight, what is the next time E all five colored lights will all flash together at the exact same time?
Choose one
A) 0:03 AM
B) 0:04 AM
C) 0:06 AM
D) 0:12 AM
E) 0:24 AM
Time taken by each light to on   Red = 20 secs   Blue = 30 secs   Green = 45 secs   Orange = 60 secs   Yellow = 80 secs   We need to take LCM to find the time all five colored lights will flash together.   LCM = 720 secs   =12 mins   =0.12 AM   Ans = 0:12 AM
<result>D</result>
The Royal Hawaiian Hotel decorates its Rainbow Christmas Tree with non-flashing white lights and a series of colored flashing lights - red, blue, green, orange, and yellow. The red lights turn red every 20 seconds, the blue lights turn blue every 30 seconds, the green lights turn green every 45 seconds, the orange lights turn orange every 60 seconds, and yellow lights turn yellow every 1 minute and 20 seconds. The manager plugs the tree in for the first time on December 1st precisely at midnight and all lights begin their cycle at exactly the same time. If the five colored lights flash simultaneously at midnight, what is the next time E all five colored lights will all flash together at the exact same time?