<PRE><B>Question 1062392</B>
In 60 minutes ( 1 hour ), the 30 minute bell
rings foor the 3rd time, 11, 11:30, and 12
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The 20 min bell rings for the 4th time:
11, 11:20, 11:40, and 12
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The 15 min bell rings for the 5th time:
11, 11:15, 11:30, 11:45, and 12
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So, at 12 AM they all ring together

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