Question

There's a string of red and blue lights strung around a window the red lights blink every three seconds and the blue lights blink every five seconds how many times will the blank at the same time in one minute

Answer 1

4 times 3x5 =15
60\15=4
Answer= 4

Answer 2

In one minute, they will blink at the same minute 4 times.

Explanation:

The amount it takes for them to blink together is the least common multiple between the time it takes for each of them to blink together.

It takes 3 seconds for the red light to blink and 5 seconds for the blue light to blink. The lcm between 3 and 5 is 15. This means that they blink together each 15 seconds.

A minute has 60 seconds. So in a minute, they are going to blink together 60/15 = 4 times.