Question

The traffic lights at three different road crossings change after every 48 seconds, 72 seconds and 108 seconds respectively. If they all change simultaneously at 6:10:00 hrs then they will again change simultaneously at:

• A. 6:17:17
• B. 6:17:10
• C. 6:17:12
• D. 6:17:22

Answer 1

Answer:

C. 6:17:12

LCM (48, 72, 108) = 432 after 432 seconds, they will change simultaneously 60 seconds = 1 minute so on dividing 432/60, we get 7 as quotient and 12 as a reminder Hence, 432 seconds = 7 min 12 seconds The time = 6:17:12