Posted by **Anonymous** on Monday, July 8, 2013 at 7:07am.

the green light flashes every 3 seconds,the red every 5 seconds and white at 10 seconds. iF they flash at 12 noon.When will they flash together again in a minute? in an hour?

- Math -
**MathMate**, Monday, July 8, 2013 at 7:55am
Both, in a minute and in an hour.

The LCM of 3, 5 and 10 is the same as the LCM of 3 and 10 because 5 divides 10 (5 is a factor of 10).

The LCM of 3 and 10 is 30.

So the soonest the will flash together is 30 seconds.

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