The document discusses different measures of central tendency, including the mean and median. It introduces the concept of using sigma notation to simplify writing out long sums, such as when calculating the mean of a data set. It provides an example of entree prices from a restaurant and encourages writing out the formula to calculate the mean using sigma notation.

2. Sigma Notation To simplify our notation when we are writing long sums (such as finding the mean), mathematicians have invented Sigma Notation . If we present our entrée costs in a list: Where Then the formula for the mean can be written using sigma notation like this:

3. Let’s explore sigma notation a bit:

4. Now, if we go back to our list of entrée prices: We said that the mean could be found using How?

5. Try writing a formula using sigma notation for the following sets of numbers: