Using the mean number for any data set based on historical data will deliver a projection. Calculating the standard deviation and T-Value against that data set results in a realistic range against ...

To calculate the mean, you add up all the numbers in the set, then divide the total by the number of numbers you added. The mean might not always be a whole number it might be a decimal.

Variance is a measurement of the spread between numbers in a data set. The variance measures how far each number in the set is from the mean. You can use Microsoft Excel to calculate the variance ...