Question

Three neon signs are turned on at the same time the first one blinks after every 10 seconds and the second one blinks after every 20 seconds and the third one blinks after every 25 seconds when will they blinks together again if they blinked last at 9:00 pm?

Answer 1

Answer:

Step-by-step explanation:

Think about mulitples of the two numbers 9 and 15. And we will have to assume that they both started blinking at the same time (at time zero)

For 9 the lights will blink at seconds: 0, 9, 18, 27, 36, 45, 54, 63,

For 15 the ligts will blink at seconds: 0, 15, 30, 45, 60, 75

They will blink together at 45 seconds