Question

a light display has three lights, each of which flashes on for an instant at regular intervals. the yellow one flashes on 15 times per minute, the blue one flashes on 6 times a minute, and the red one flashes on 12 times a minute. you see all three lights flash on simultaneously. how much longer must you wait before the three lights flash on simultaneously again?

Answer 1

Here is your answer... ^_^

⭐red light flash in interval  of 20 second
⭐green ----------//-------------of 15 second
⭐yellow ------------//---------- of 10 second
⭐interval 75*60 second
⭐lcm of (20,15,10) =60
⭐that means every 60 second they flash together once!
⭐75*60/60=75
⭐they flash together 75 times

Hope it helps you out ⭐^_^⭐
Thanks ⭐(^^)⭐