probability

purpose of probability

basic notation

the probability scale

formula for calculating basic probability values

calculating the probablity of an event not occuring

sample space diagrams

relative frequency

expected value

expected frequency

DEFINITION: the number of times we would expect an event to occur over a given number of trials that take place during an experiment

P(A) - probability that event A will occur.. P(A′) - probability of the complement of event A.

CALCULATION: to find the expected frequency, we multiply the probability of that event taking place by the number of trials of the experiment.

DEFINITION: a measure of central tendency; a value for which the results will tend to.

CALCULATION: the average or mean value of the outcomes of that variable

DEFINITION: P(A) = f / N

FORMULA: To find the expected value, E(X), or mean μ of a discrete random variable X, simply multiply each value of the random variable by its probability and add the products. The formula is given as E ( X ) = μ = ∑ x P ( x )

Probability provides information about the likelihood that something will happen.

Meteorologists, for instance, use weather patterns to predict the probability of rain. In epidemiology, probability theory is used to understand the relationship between exposures and the risk of health effects.

P(A|B) - conditional probability that event A occurs, given that event B has occurred

P(A∩B) - probability of the intersection of events A and B.

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