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 Marbles Bonanza (Posted on 2003-09-08)
You have an empty container, and an infinite number of marbles, each numbered with an integer from 1 to infinity.

At the start of the minute, you put marbles 1 - 10 into the container, then remove one of the marbles and throw it away. You do this again after 30 seconds, then again in 15 seconds, and again in 7.5 seconds. You continuosly repeat this process, each time after half as long an interval as the time before, until the minute is over.

Since this means that you repeated the process an infinite number of times, you have "processed" all your marbles.

How many marbles are in the container at the end of the minute if for every repetition (numbered N)

A. You remove the marble numbered (10 * N)

B. You remove the marble numbered (N)

 Submitted by levik Rating: 3.6154 (13 votes) Solution: (Hide) Thinking about it logically, in case of (A), every 10th marble is removed, so after an infinity of repetitions, there will still be an infinite number of marbles in the container. However, in case of (B), because the marbles get removed sequentially, one would think that after an infinity of repetitions, every marble has been removed and the container is empty.

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