Random variables that have countable numbers of values, usually taking values like zero and positive integers

Random variables that are not integers but take values that lie in an interval

A probability function of a continuous random variable

The distribution is symmetrical with most of the data clustered around the centre close to the mean

The probabilities for the data further from the mean taper off equally in both directions

the notation used for a continuous random variable X which has a normal distribution

their positions and the width of the graphs depend on their respective mean, and standard deviation

The larger the mean value, the more to the right the position of the graph

The height of the graph increases when the standard deviation value decreases if mean is kept constant