1115 Basic probability

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11/15 Basic probability Probability in our
context has to do with the outcomes of repeatable
experiments Need an Experiment Set X of
outcomes (outcome space) from the experiment
They should be disjoint (mutually exclusive) and
exhaustive (include all possible
outcomes) Events are sets of outcomes (subsets
of the outcome space). We want to be able to
assign a probability that an event E will occur
when the experiment is repeated.
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• 11/15 Basic properities of a probability
  function.
• Outcomes S x1, x2, x3,
• E, F events
• 1. P(E) gt 0 for any event E.
• 2. P(S) 1
• If E and F are mutually exclusive, then
• Consequences
• 4.
• 5.

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Calculating probabilities in games Poker
What is the probability of getting a flush in a
random 5 card hand? What is the probability
of getting at least a pair in a random 5 card
hand?
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• Common 3 20 card deck 4 aces, 4 2s . 4 5s
• 3 cards are dealt
• i) Event E at least 2 4s (maybe 3)
• Event E no two cards have same value

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Calculating probabilities in games Common 15