Question

The traffic lights at three different road crossings change after every 48 seconds,72 seconds and 108 seconds respectively. If they change simultaneously at 7 a.m,at what time will they change simultaneously again​

Answer 1

Answer:

We know that in order to find the time when the three lights will change simultaneously again after 7 a.m., we need to find the LCM of 48, 72, and 108. Hence, converting 432 seconds into minutes and seconds, we get: 432 seconds = 7 minutes and 12 seconds.

Answer 2

Answer:

7 minutes 12 seconds past 7 a.m.

Step-by-step explanation:

LCM of 48 seconds, 72 seconds and 108 seconds.

48 = 2×2×2×2×3

72 = 2×2×2×3×3

108 = 2×2×3×3×3

LCM= 2×2×2×2×3×3×3

= 432

Now,

So, divide 432 by 60...

We will get 7.2 seconds..

Now,

1 minute = 60 seconds

So, 7 minutes = 7×60 seconds= 420 seconds.

Now, Subtract 432 and 420...

= 4 3 2

- 4 2 0

0 1 2

☆Hence, 432= 7 minutes 12 seconds...

So, at 7 minutes 12 seconds past 7 a.m., they will change simultaneously again...