The least common multiple that is divisible by both a and b is the smallest positive integer. They will change simultaneously at 8:27:12 Hrs. The correct option is A.
What is LCM?
The least common multiple that is divisible by both a and b is the smallest positive integer, lowest common multiple, or smallest common multiple of two numbers a and b, generally indicated by LCM.
Given The traffic lights at three different road crossings change after every 48 sec; 72 sec; and 108 sec., respectively. Therefore, the time they all take to change simultaneously is the LCM of 48, 72, and 108., which is 432.
Therefore, every 432 seconds or 7 minutes and 12 seconds, all the three lights will change simultaneously.
Now, as given they all change simultaneously at 8:20:00 hrs, then they will again change simultaneously next time after 432 seconds, therefore, they will change simultaneously at 8:27:12 Hrs.
Hence, the correct option is A.
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