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 Away from home (Posted on 2012-10-23)
Last year John left his home and returned seven whole months to the day.

What is the probability he was absent for exactly 215 days?

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There were 365 days in 2011, last year.
The only month in which John could have left and returned seven whole months to the day, for an absent period of 215 days, is July. The returning month would have been February of the year, 2012, following the date of departure. Given that February has 29 days during a leap year, the date of departure could have been anytime between the 1st and the 29th. A departure on July 30 or 31 could not have a return day seven whole months to the day as February has no 30th or 31st, thus only 29 days could be the extent of consideration of the month of departure an absence of 215 days for the given period and criteria. Therefore, the probability would be 29/365, or approximately 7.9452%.

 Posted by Dej Mar on 2012-10-23 12:52:34

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