I am looking for help to solve this type of problem.

Question

If one stoplight blinks 12 times per minute. another blinks 10 times per minute. after how many minutes will both of the stoplights blink at the same time?

Answer 1

They will both blink at the same time when they both share the Greatest Common Factor (GCF) of the object with the smaller value. The smaller value is 10 and its GCF is 10. So when 12 becomes a multiple of 10 they will blink at the same time. Listing multiples of 12:

 

12, 24, 36, 48, 60.

 

They will blink at the same time after 60 blinks by 12, which happens in five seconds. You can verify this by 5 x 12 = 60.