A parking spot is unoccupied 1/3 of the time…
But, you find it empty for nine consecutive days in a row.
Find the probability that it will be empty on the tenth day.
The answer is 2/3 but I can't figure out how that is possible. It should be 1/3 instead.
Best Answer
After actually reading through that article (a painful experience considering that the author clearly doesn't know enough about the subject material to write precise explanations or complete descriptions of the questions), it is obvious that he got the wording mixed up. He would have meant either "the space is occupied $1/3$ of the time" or "the answer is still $1/3$."
But I would take this a step further: there is an underlying assumption being made that the probability of the space being occupied on any given day is independent of whether it was occupied on a previous day. The expected value of the proportion of days on which it is unoccupied may be $p$, but if individual days are not independent of each other (which is a valid model, since for example, weekends might be different than weekdays), then the conditional probability is no longer memoryless and you might use a Markov chain model, for instance.