Question

please solve my question with explanation​

Answer 1

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

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 432 that is after 432 second they will change simultaneously 432 sec= 7 min 12 sec.