a background to understanding probability is understanding set theory, as venn
diagrams and intersections/unions are often used to denote the events we need
to figure to determine probability.

definitions

1. sample point: each possible outcome of an experiment
2. an event is the outcome of an experiment. event: sample point
3. sample space: all possible outcomes. The symbol S will be used to denote the sample space.
4. If the events A and B have no common basic outcomes, they are <pre><em>mutually exclusive</em></pre> and their intersection A ïf‡ B is said to be the empty set indicating that A ïf‡ B cannot occur. For example, tossing a die once we can't get a 2 and a 4.
5. union of A and B: probability of A or B occurring. 1. disjoint set: their intersection is the null set.
6. intersection of A and B: The probability of both a and b occurring. This is apparent from the Venn diagram
7. union of A and B: probability of A or B occurring. For example, the probability that atleast one head will occur when a coin is tossed. This will be P(A1 union A2) = P(A1)+P(A2) - P(A1 intersection A2)
8. mutually exclusive: the intersection of A and B is the empty set indicating that A intersection B cannot occur.
9. mutually exhaustive:
10. collectively exhaustive: the union of all the elements in the set is S {the whole sample space }
11. The possible outcomes of a random experiment are called the basic outcomes and the set of all basic outcomes is called the sample space.