1. Section 8.2: Relative Frequency

2. Objective(s):
By following instructions, students will be able to:
Recognize possible associations and trends between two categories of categorical data.

3. Def: joint frequency is found by dividing a frequency that is not in the total row or total column by grand total. It tells what proportion of the total has both of the two specified characteristics.
Def: marginal relative frequency is found by dividing a row total or a column total by the grand total. It tells what portion of the total has a specified characteristic.

4. Preferred Social Media
explain 1A
Complete a two-way relative frequency table from the data in a two way frequency table. Identify the joint relative frequencies and the marginal relative frequencies.
Preferred Social Media
Grade
Facebook
Instagram
SnapChat
Total
9th 6 12 18 36
10th 14 20 10 44 32 28 80

5. explain 1B
Millie performed a survey of students in the lunch line and recorded which type of fruit each student selected along with the gender of each student. The two-variable frequency data she collected is shown in the table.
Fruit
Gender
Apple
Banana
Orange
Total
Girl 16 10 14
Boy 25 13

6. Like Aerobic Exercises
Your-Turn #1
Find the joint relative frequencies and marginal relative frequencies.
Like Aerobic Exercises
Like Weight Lifting
Yes No
Total 7 14 12

7. Def: conditional relative frequency describes what portion of a group with a tgiven characteristic also has another characteristic. A conditional relative frequency is found by dividing a frequency that is not in the total row or the total column by the total for that row or column.

8. Preferred Social Media
explain 2A
Use the data from Explain 1A. Find the conditional relative frequency that a person in the survey prefers Instagram, given that the person is in the ninth grade.
Preferred Social Media
Grade
Facebook
Instagram
SnapChat
Total
9th 6 12 18 36
10th 14 20 10 44 32 28 80

9. explain 2B
Use the data from Explain 1B. Find the conditional relative frequency that a student in Millie’s survey chose an orange, given that the student is a boy.
Fruit
Gender
Apple
Banana
Orange
Total
Girl 16 10 14
Boy 25 13

10. Your-Turn #2
What is the conditional relative frequency that a student likes to lift weights, given that the student does not like aerobics?

11. Objective(s):
Did we…
Recognize possible associations and trends between two categories of categorical data?

12. HW:
Sec 8.2 pg 296 #s 1-19