A bell rings every 18 minutes. A second bell rings every 24 minutes. A third bell rings every 32 minutes. If all the three bells ring at the same time at 8 o'clock in the morning, at what other time will they all ring together?
- A12:40 hrs
- B12:48 hrsCorrect
- C12:56 hrs
- D13:04 hrs
Explanation
To find when all three bells will ring together again, we need to find the Least Common Multiple (LCM) of their individual ringing intervals.
-
Identify the intervals: The bells ring every 18 minutes, 24 minutes, and 32 minutes.
-
Calculate the LCM of 18, 24, and 32:
- Prime factorization:
- 18 = 2 x 3^2
- 24 = 2^3 x 3
- 32 = 2^5
- LCM = 2^5 x 3^2 = 32 x 9 = 288 minutes.
- Prime factorization:
-
Convert the LCM from minutes to hours and minutes:
- 288 minutes / 60 minutes/hour = 4 hours and 48 minutes (since 4 x 60 = 240, and 288 - 240 = 48).
-
Add this duration to the initial ringing time:
- Initial time: 8:00 AM
- Add 4 hours 48 minutes: 8:00 + 4:48 = 12:48 PM.
Therefore, all three bells will ring together again at 12:48 hrs.
Analyzing the options: A) 12:40 hrs - Incorrect. B) 12:48 hrs - Correct, as it matches our calculation based on the LCM. C) 12:56 hrs - Incorrect. D) 13:04 hrs - Incorrect.
The final answer is B.

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