Question

A red light blinks 3 times per minute and a green light blinks 5 times in 2 minutes at regular intervals. If both lights start blinking at the same time, after what time do they blink together?​

Answer 1

ANSWER:

30 TIMES

SOLUTION:

The red light flashes every 60/3 = 20 seconds and the green light flashes every 120 / 5 = 24 seconds

LCM of 20 and 24 = 120 second = 2 minutes

So after the first flash, they will flash together 60/2 = 30 times