Normal Curves and Sampling Distributions Chapter 7

Important Properties of a Normal Curve

Empirical Rule For a distribution that is symmetrical an bell-shaped (in particular, for a normal distribution): Approximately 68% of the data values will lie within 1 standard deviation on each side of the mean. Approximately 95% of the data values will lie within 2 standard deviations on each side of the mean. Approximately 99.7% of the data values will lie within 3 standard deviations on each side of the mean.

Z Scores

Standard Normal Distribution

Using a Standard Normal Distribution Table See Table 3 of the appendix Find the area to the left of z = -1.1 Find the area to the left of z = 1.2 Find the area to the right of z = 1.2 Find the area between z = -1.1 and z = 1.2