## Lesson 4: Measuring Variance and Standard Deviation

September 4, 2019

Review:

- Measures of Center
- Boxplots
- Alternative for boxplots: http://www.imathas.com/stattools/boxplot.html

- Attendance

Presentation:

- Demonstrate calculation
- Find the variance and the standard deviation for the following (n=10) exam scores: 80 73 92 85 75 98 93 55 80 90
- Demonstrate in Google Sheets

- Video

Activity:

**Problem 1.** Below are the number of home runs that Babe Ruth hit in each of his 15 years with the New York Yankees, 1920 – 1934. Calculate the mean and standard deviation.**54 59 35 41 46 25 47 60 54 46 49 46 41 34 22 **

**Problem 2.** Six 9th-grade students and six 12th-grade students were asked: how many movies have you seen this month? See their responses below. Calculate the mean and standard deviation for each data set. Which is more spread out, the 9th-grade or 12th-grade data?

9th-grade: **5, 1, 2, 5, 3, 8**

12th-grade: **4, 2, 0, 2, 3, 1**

Assignment:

- Repeat Problems 1 and 2 (above) using Sheets
- Using the Student Height Data, calculate mean and standard deviation in Sheets
- Text Ch. 1, p. 40-44