Chapter 6

Probability and Statistics

Properties of a Normal Curve

- The normal curve is symmetrical about the mean (u).

- The curve should be bell-shaped.

- The mean is at the middle and divides the area into halves.

- The total area under the curve is equal to 100% or 1.

It is completely determined by its mean and standard deviation (o).

Empirical Rule

- The empirical rule states that for a normal distribution, nearly all of the data will fall within three standard deviations of the mean.

- 68% of the data falls within the first standard deviation from the mean.

- 95% of the data falls within two standard deviations from the mean.

- 97% (or nearly all) of the data falls within three standard deviations from the mean.

Finding Sample Mean and Standard Deviation

How to find u and o

- u is equal to the simple average of the numbers.

- To find o, subtract the mean and square the answer.

- After doing this for all of the values, take the average.

- Lastly, take the square root of the average of the values and that gives o.