that's not exactly what I'm looking for. Let me put it this way...
Take a deck of cards, remove the aces. Shuffle thoroughly. Select 12 cards
at random of the 48. What are the odds that *none* of the 12 cards you
selected will be face cards?
Let's look at the probability that someone NOT in your group wins.
Probability = Number of people NOT in your group/total number of people
First Pick: 186/254 = 73.2%
Last Pick: 175/243 = 72.0%
(assuming once the name is picked, it is not put back)
So, the odds of a non staff member being picked remain at about 72.5% for
all drawings.
The larger group that does not include your staff will always have a
higher
chance of winning. I think you have fallen into the probability trap that
assumes that the events are dependent on each other. Each drawing is in
fact, independent of the previous drawings, so the chance of a non-staff
member being selected is always the number of the non-staff members
remaining divided by the total number of people remaining.
See
http://www.mathsrevision.net/gcse/pages.php?page=32
Hope this helps,
Jim Maki
[EMAIL PROTECTED]
