LCM and HCF Practice Test 1

Question : 1 of 40

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The traffic lights at three different signals change after 30 seconds, 45 seconds and 60 seconds respectively. If they all change simultaneously at 11:27 am, then at what time will they again change simultaneously?

11:30 am
12:03 pm
11:42 am
12:00 noon
None of these

Validate

Solution:

LCM of (30, 45 and 60) = 180
Thus, lights will change simultaneously after

180/60 = 3

minutes.
So, at 11:30 a.m. they will change simultaneously.

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