In calculating the desired sample size which we denote as little n, we must determine the following values:

• The variance.
• The range.
• The total population.
• The desired error of the estimate.

The variance is roughly equal to the range which we determined to be a value of 3 divided by 4; or 3/4.
The desired error of the estimate at a 95% confidence estimate is point 25 or 1/4.

The numerator for our calculation of sample size in the total Population (designated as capital N) times the variance squared.

The denominator for our calculation of sample size is the desired error of the estimate squared and then divided by 4. This value is then multiplied by the total population less one. Finally the value for the denominator is completed by adding the resultant value previously to the value of the variance squared.

By dividing the numerator by the denominator, the sample size is determined.