The Normal Distribution


a normal distribution is a probability distribution of a continuous random variable with a bell-shaped frequency curve.

a normal distribution and normal curve are symmetrical about the mode, median and mean.

many distributions in real life are approximately normal distributions. e.g. heights and weights of a large group of people, lengths of leaves on a tree, etc.

the standard deviation gives a measure of the spread of the values around the mean.

probabilities associated with normal distributions can be found in tables.

Key Skills

solve problems involving normal distributions.


normal distributionnormal curve, standard normal curvestandard deviationmeanmedianmodez-score, symmetry