Statistics

1. Statistics Consider the results form a class quiz: Boys: 54, 84, 70, 72, 92, 32, 92, 78, 80 Girls: 52, 74, 84, 94, 70, 68, 88, 80 Put the data in order from least to greatest: Boys: Girls:

2. To summarize the data, we use measures of central tendency: Mean: (a.k.a. average) add up the numbers and divide by the number of data Mean (boys) =

3. Median: the middle number when the data is written in order  If there is an even amount of data, average the two middles Median (boys) =

4. Mode: the number that occurs most frequently in the data  There may be no mode or several modes Mode (boys) =

5. To tell how spread out the data is, we use measures of dispersion: Range: the difference between the largest and smallest numbers in the data Range = (greatest value) – (least value) Range (boys) =

6. Standard Deviation: describes the typical difference between the mean and a data value Std. Dev. (boys) =

7. To help us visualize the data, we can use a Box & Whisker Plot • Put the data in order from least to greatest. • Find the minimum and maximum values • Find the median • Find the Lower Quartile (median of the lower half of the data) • Find the Upper Quartile(median of the upper half of the data) • Plot the five values on a scaled number line • Draw the boxand whiskers

8. Ex. Make a box-and-whisker plot for the boys scores.

9. Ex. For the girls scores, find the following: Mean: Median: Mode: Range: Standard Deviation: Box-and-whisker Plot:

10. Please do the review and finish it at home. This is the last lesson from the chapter, the test will be on next class.