Six bells ring at intervals of 2, 4, 6, 8, 10 and 12 seconds respectively. Once, when they start ringing simultaneously for the first time, then determine how many times they will ring together in a continuous span of 30 minutes?

16 times

The correct answer is Option (4) → 16 times

The bells will ring together at intervals equal to the LCM of their ringing times.

Intervals given:
2, 4, 6, 8, 10, 12 seconds

Step 1: Find LCM

LCM(2, 4, 6, 8, 10, 12) = 120 seconds

So, the bells ring together every 120 seconds.

Step 2: Total time

30 minutes = 30 × 60 = 1800 seconds

Number of times they ring together:

$\frac{1800}{120} = 15$

Including the first simultaneous ringing at the start,

$15 + 1 = 16$