(New page: The opposite or complement of an event A is(that is, the event of A not occurring)is <math>P(A') = 1 - P(A)\,</math> If two events, A and B are independent then the joint probability...) |
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If two events are mutually exclusive then the probability of either occurring is | If two events are mutually exclusive then the probability of either occurring is | ||
| − | <math>P(A\mbox{ or }B) = P(A \cup B)= P(A) + P(B) | + | <math>P(A\mbox{ or }B) = P(A \cup B)= P(A) + P(B)</math> |
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If the events are not mutually exclusive then | If the events are not mutually exclusive then | ||
| − | <math>\mathrm{P}\left(A \hbox{ or } B\right)=\mathrm{P}\left(A\right)+\mathrm{P}\left(B\right)-\mathrm{P}\left(A \mbox{ and } B\right).</math> | + | <math>\mathrm{P}\left(A \hbox{ or } B\right)=\mathrm{P}\left(A\right)+\mathrm{P}\left(B\right)-\mathrm{P}\left(A \mbox{ and } B\right)</math> |
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| + | Conditional probability is written ''P''(''A''|''B''), and is read "the probability of ''A'', given ''B''". | ||
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| + | <math>P(A \mid B) = \frac{P(A \cap B)}{P(B)}\,</math> | ||
Revision as of 13:51, 11 April 2010
The opposite or complement of an event A is(that is, the event of A not occurring)is
$ P(A') = 1 - P(A)\, $
If two events, A and B are independent then the joint probability is
$ P(A \mbox{ and }B) = P(A \cap B) = P(A) P(B)\, $
If two events are mutually exclusive then the probability of either occurring is
$ P(A\mbox{ or }B) = P(A \cup B)= P(A) + P(B) $
If the events are not mutually exclusive then
$ \mathrm{P}\left(A \hbox{ or } B\right)=\mathrm{P}\left(A\right)+\mathrm{P}\left(B\right)-\mathrm{P}\left(A \mbox{ and } B\right) $
Conditional probability is written P(A|B), and is read "the probability of A, given B".
$ P(A \mid B) = \frac{P(A \cap B)}{P(B)}\, $
