Probability Language and Basic Rules

The sample space S is the set of all possible outcomes of a random experiment. An individual outcome is a sample point; an event A is a subset of S. The whole space S is the certain event, and is the impossible event. The complement A contains the outcomes for which A does not occur. 0 <= P(A) 1, P()=0, P(S)=1. P(A)=1-P(A), =S, S =. For equally likely outcomes in a finite sample space, P(A)= n(A)n(S), where n(A) counts the favourable outcomes and n(S) counts all outcomes. From repeated trials under the same conditions, estimate P(A) by the relative frequency number of occurrences of Anumber of trials. The estimate can fluctuate from one set of trials to another. When a point is chosen uniformly from a region of finite, nonzero length, area or volume, P(A)= measure of the favourable regionmeasure of the whole region. Use the same measure and units in numerator and denominator. This ratio does not apply to non-uniform selection.