At what time will three light house flash at the same time if one flashes every 45 seconds, the?

Question

...  seconds flashes every 1.25, and the third flashes every 2 minutes that starts at 8:00 am

Answer

8:30 am 

If you need work:

If you convert all times to seconds (45, 75, 120).
Then use prime factors to find the Lowest Common Multiple
(45: 3,3,5) (75: 3,5,5) (120: 2,2,2,3,5)

LCM: 2*2*2*3*3*5*5 = 1800 seconds
convert 1800 seconds back to minutes (1800/60=30)

Every 30 minutes the lighthouses should flash together.

At what time will three light house flash at the same time if one flashes every 45 seconds, the?

Answers (1)