The manager of the cost accounting department of a large computer manufacturing firm always tells three jokes during her monthly report to the board of directors in an attempt to inject a bit of levity into an otherwise sobering presentation. She has an inventory of a dozen different jokes from which she chooses three to present for any given monthly report.

a. If she chooses the three jokes randomly from the inventory of 12 each month, what is the probability that, in any given month, at least one of the three jokes will be different from the jokes she told the month before?

b. If she chooses the three jokes randomly from the inventory of 12 each month, what is the probability that, in any given month, all three jokes will be different from the three she told the month before?