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 8 p.m., at what time will they change simultaneously again?

Answer 1

they chance after 8:07:12

Answer 2

48 , 72 , 108 divide by 3
16, 24 , 36. divide by 2
8 , 12, 18. divide by 2
4 , 6 , 9. divide by 2
2, 3, 9. divide by 3
2 , 1, 3. process end
3×2×2×2×3×2×3 = 432
$\frac{432}{60} = 7.2$
08:07:02 this time, they will change simultaneously