A light display has three colored lights, each of which

Last updated: 7/12/2022

A light display has three colored lights, each of which flashes on for an instant at regular intervals. The yellow one flashes 15 times per minute, the blue one flashes 6 times per minute, and the red one flashes 12 times per minute. You see all three lights flash on simultaneously. How much longer must you wait before the three lights flash on simultaneously again? The correct answer is 20 seconds. Solve this problem and explain each step of your process so that a 5th grader will understand.