TRAFFIC LIGHTS!!
Number Theory
Level
1
The traffic lights at three different road crossings change after every 48s, 72s & 108s. If they all change simultaneously at 8:20 hrs, then at what time will they again change simultaneously?
8:27:24 hrs
8:27:48 hrs
8:27:36 hrs
8:27:12 hrs
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Since L.C.M of 48, 72, 108 is 432 and it is in seconds, we have to divide it by 60 to convert into minutes.By dividing 432 by 60 we get 7.2
therefore by adding 7.2 to 8:20, we get 8:27:12
therefore the time at which they again change simultaneously is 8:27:12