JIPMAT 2025 (QA) - The traffic lights at three different road crossings change after every 48 sec, 72 sec and 108 sec, respectively. They all change simultaneously at 08:20:00 hours, when will they again change simultaneously? | PYQs + Solutions

JIPMAT 2025

Number System

HCF & LCM

Medium

The traffic lights at three different road crossings change after every 48 sec, 72 sec and 108 sec, respectively. They all change simultaneously at 08:20:00 hours, when will they again change simultaneously?

9:27:12 hours

8:27:12 hours

7:27:13 hours

11:00:12 hours

✅ Correct Option: 2

Required time

=\mathrm{LCM}

of 48 , 72 and 108 seconds

\begin{array}{c|ccc} 2 & 48,72,108 \\ \hline 2 & 24,36,54 \\ \hline 2 & 12,18,27 \\ \hline 3 & 6,9,27 \\ \hline 3 & 2,3,9 \\ \hline & 2,1,3 \end{array}

LCM

=2 \times 2 \times 2 \times 2 \times 3 \times 3 \times 3

=432

seconds

=7

minutes

12

seconds

\therefore

They will beep after 7 minutes and 12 seconds together so after 8:20:00 hours, they will beat together at 8:27:12 hours.