Question 1127797: You have a string of blinking lights. The blue lights blink every 5 seconds and the red lights blink every 3 seconds. How many times will the lights blink at the same time in one minute.
Found 2 solutions by addingup, MathTherapy:
Answer by addingup(3677)   (Show Source):
You can put this solution on YOUR website!
Numbers divisible by 5 are those ending in 5 and 0. Thus, they will blink together every time a multiple of 3 is 5 or 0:
:
3,6,9,12,(15),18,21,24,27,(30),33,36,39,42,(45), 48, 51, 54, 57, (60)
You can count the times, I put them in parenthesis.
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
You have a string of blinking lights. The blue lights blink every 5 seconds and the red lights blink every 3 seconds. How many times will the lights blink at the same time in one minute.
LCM of 5 and 3, from its first, 15 to its last, 60!
List and count them!
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