PMPs (project management professionals) often apply basic statistics to their projects. For the PMP certification exam, here's what you need to know when dealing with normal and cumulative distributions:

Equations are based on a normal distribution. In a normal distribution, keep the following in mind:

68.3% of the data points fall within one standard deviation.

95.5% of the data points fall within two standard deviations.

99.7% of the data points fall within three standard deviations.

If you're looking at a normal curve and need a cumulative distribution, you should remember these values:

0.15% of the data points fall between 0 and –3 from the mean.

2.25% of the data points fall between 0 and –2 from the mean.

16% of the data points fall between 0 and –1 from the mean.

84% of the data points fall between 0 and +1 from the mean.

97.75% of the data points fall between 0 and +2 from the mean

99.85% of the data points fall between 0 and +3 from the mean.