Question

The trafic lights at three different road crossing change after 48 seconds ,72seconds and 108 seconds lcm

Answer 1

Answer:

Given that traffic light at three different road crossing change after every 48 seconds,72 seconds and 108 seconds respectively.

So let us take the LCM of the given time that is 48 seconds, 72 seconds, 108 seconds

48 = 2 × 2 × 2 × 2 × 3

72 = 2 × 2 × 2 × 3 × 3

108 = 2 × 2 × 3 × 3 × 3

Hence LCM of 48, 72 and 108 is (2 × 2 × 2 × 2 × 3 × 3 × 3) = 432

So after 432 seconds they will change simultaneously

We know that 60 seconds = 1 minute

so on dividing 432 / 60 we get 7 as quotient and 12 as reminder

Hence, 432 seconds = 7 min 12 seconds

Therefore the time is = 7 a.m. + 7 minutes 12 seconds

Hence the lights change simultaneously at = 7:07:12 a.m

Answer 2

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