Normal Curves Often good representation of real data Often good approximations of chance outcomes

Normal Curves are symmetric, so the mean will equal the median and be in the center The standard deviation is at the point where the slope stops increasing and starts decreasing

The rule In any Normal distribution: 68% of observations fall within one standard deviation of the mean 95% within two standard deviations 99.7% within three standard deviations

For a distribution, we have labelled the mean as x in a Normal distribution the mean is usually labelled as “mu”  Standard deviation has been s, for a normal distribution it is labelled “sigma” 