The geometric mean is the average of a set of products, the calculation of which is commonly used to determine the performance results of an investment or portfolio.

Formula of Mean: Know to How to Calculate Median for Grouped, Ungrouped data along with solved examples, questions with solution.

The article How to Calculate an Average Percentage Difference Between Two Dollar Amounts originally appeared on Fool.com. Try any of our Foolish newsletter services free for 30 days .

The following article will show you, step-by-step, how to calculate the historical variance of stock returns with a detailed example.