Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and…

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Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively. In 30 minutes, how many times do they toll together?

Answer: D. 16Step-by-Step Calculation 1. Find the LCM of the intervals: The intervals are 2, 4, 6, 8, 10, and 12 seconds. Prime factorization: 2 = 2 4 = 2^2 6 = 2 * 3 8 =…

  1. A.

    24

  2. B.

    21

  3. C.

    15

  4. D.

    16

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Correct answer: D

Step-by-Step Calculation
1. Find the LCM of the intervals:
The intervals are 2, 4, 6, 8, 10, and 12 seconds.

Prime factorization:

2 = 2

4 = 2^2

6 = 2 * 3

8 = 2^3

10 = 2 * 5

12 = 2^2 * 3

Taking the highest power of each prime factor present (2^3, 3^1, 5^1):

LCM = 8 * 3 * 5 = 120 seconds.

This means the bells toll together every 120 seconds, or every 2 minutes.

2. Calculate the number of intervals in the total duration:

Total time = 30 minutes.

Number of intervals = Total time / Interval time = 30 / 2 = 15 intervals.

3. Account for the initial toll:

Since the bells start by tolling together at time zero, we must add that initial event to the 15 intervals that occur during the 30-minute duration.

Total tolls = 15 + 1 = 16 times.

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