# PROBABILITY TERMINOLOGY

```PROBABILITY
(The Basic Concepts)
probability: a number that gives a measure of
how likely an event is to occur
(the mathematics of chance)
TERMINOLOGY
experiment: a sequence of trials in which a physical
occurrence is observed
outcome: the result that is observed in the experiment
sample space (S): the set of all possible outcomes for an
experiment
event (E): a subset of the sample space
Example 
Observing at least one head in the toss of two coins.
List the sample space and the event.
There are 3 basic type of probability:
1.
EMPIRICAL (EXPERIMENTAL) PROBABILITY:
 experiments are used to compile data to calculate
the probability (based on direct observation)
# of times event occurs
 P(E) 
# of times exp eriment repeated
2.
THEORETICAL PROBABILITY:
 based on mathematical analysis (theory and models)
n(E)
 P(E) 
n(S)
where n(E) is the # of outcomes in the event and
n(S) is the # of outcomes in the sample space
3.
SUBJECTIVE PROBABILITY:
 based on intuition and previous experience
HOMEWORK: p.312 #1abf, 2
```