2. Measures of Center

3. Sigma- A symbol for sum. ∑ Summation Notation- The use of the sigma symbol to represent a summation. Also called sigma-notation or ∑-notation. Mean- Average of the data set. Median- Middle value of the data set. Mode- Value of the data set that appears most often. Measures of Center- The mean and median of a data set. Also known as measures of central tendency. Extremes- Outlier values in a data set that can distort the mean.

4. X 1 =12 X 2 =15 X 3 =18 X 4 =21 X 5 =24 X 6 =27 4 ∑ X i = X 1 +X 2 +X 3 +X 4 =12+15+18+21= 66 i=1 Number below the sigma symbol- First value of summation Number above the sigma symbol- Last value of summation

5. X 1 =23 X 2 =24 X 3 =27 X 4 =31 X 5 =32 X 6 =37 5 ∑ X i = i=2

6. Mean- Add up all values, divide by number of values. __ X = mean Median- Middle value of data set. Put numbers in order smallest to largest, then find the number in the middle. Mode- Value that appears most often.

7. 1 11 7 4 2 11 1 6 9 10 12 1 Mean? Median? Mode?

11. Worksheet 1-3