Professor X smokes a pipe. He carries two identical matchboxes, originally containing 20 matches each. When he lights his pipe, he chooses a matchbox at random and lights his pipe with one match and discards the used match.
There will come an occasion when he first selects a matchbox with only one match in it. At this point, what is the expected number of matches in the other box?
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Professor X smokes a pipe. He carries two identical matchboxes, originally containing 20 matches each. When he lights his pipe, he chooses a matchbox at random and lights his pipe with one match and discards the used match.
There will come an occasion when he first selects a matchbox with only one match in it. At this point, what is the expected number of matches in the other box?
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