1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up: Solve in your notes! NO KWL
Find the mean and median of each data set.
1. 14,24,12,20,15,22,12
mean:17 ; median:15
2. 7,13,16,9,15,6
mean:11 ; median:11

3. Problem of the Day
Jeff is painting a wall that is 20 feet long and 9 feet high. How many square feet of wall is he painting?
180 sq ft

4. Learn calculate, interpret, and compare measures of variation in a data set.

5. Vocabulary box-and-whisker plot quartiles variation
inter-quartile range (IQR)

6. Ms. Snow asks some of her students how many pets they have
Ms. Snow asks some of her students how many pets they have. The responses are 9, 0, 4, 1, 1, 2, 3, 5, and 2 pets.
Quartiles are three values, one of which is the median, that divide a data set into fourths. Each quartile contains one-fourth, or 25%, of the data.

7. The interquartile range (IQR) is the difference between the first and third quartiles.
It is a measure of the spread of the middle 50% of the data.
A small interquartile range means that the data in the middle of the set are close in value.
A large interquartile range means that the data in the middle are spread out.

8. Additional Example 1: Making a Box-and-Whisker Plot
The average number of hours that several students watch television in a day is given. Use the data to make a box-and-whisker plot: 2, 1, 5, 2, 1, 2, 3, 2, 2.
Step 1 Order the data from least to greatest.
1, 1, 2, 2, 2, 2, 2, 3, 5
Step 2 Find the least and greatest values, the median, and the upper and lower quartiles. 2 5 1 3
Least value
Greatest Value
Third Quartile
Median
First Quartile
1.5
2.5

10. Additional Example 2: Finding the Interquartile Range
Find the inter-quartile range for the data set 87, 71, 72, 73, 84, 92, 73.
71, 72, 73, 73, 84, 87, 82
Order the data from least to greatest.
84,
73,
71,
72, 82
87,
Find the median and quartiles
IQR=87-72=15
Find the difference between the first quartile (72) and the third quartile (87).
The inter-quartile range is 15.

11. Order the data from least to greatest.
Check It Out: Example 2
Find the inter-quartile range for the data set 17, 39, 38, 9, 29, 40, 27
9, 17, 27, 29, 38, 39, 40
Order the data from least to greatest.
38,
29, 9,
17,
27, 40
39,
Find the median and quartiles
IQR=39-17=22
Find the difference between the first quartile (17) and the third quartile (39).
The inter-quartile range is 22.

12. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

13. Lesson Quiz
A park ranger measures the thickness of ice on a
lake in 8 different locations: 19 in., 17 in., 15 in.,
15 in., 18 in., 12 in., 16 in., 14 in.
2. Find the interquartile range of the data.
3 in.

14. Lesson Quiz for Student Response Systems
The number of text messages 7 people sent in one day are as follows: 8, 4, 3, 17, 2, 1, and 10.
1. Find the inter-quartile range of the data.
A. 2.5
B. 3
C. 8
D. 9.5
2.Find the mean absolute deviation of the data, to the nearest tenth.
A. 3
B. 4.5
C. 6.4
D. 17