Test Monopoly®:

When playing "Monopoly" as part of a chain promotion, the published odds of winning are that of finding the one "rare" piece in every set.

Assuming you have the one "rare" token of a three piece set (of course, there is no way to know that at the time), how many more tokens will you need to acquire before you have a complete set?  To work this I assumed 17 non rare tokens with an 18th being reserved for "instant win" and rare tokens of other sets.

To get just one piece (or the one last piece) needs about 12 for a 50-50 chance and over 50 for a 19/20 chance in your favor.  To complete a three piece set monopoly2.htm or a four piece set (railroads) monopoly3.htm.  Of course, the object is for you to come back often.
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