Relative Frequency

Relative Frequency

NC Standards

NC.8.SP.4

Understand that patterns of association can also be seen in bivariate categorical data by displaying frequencies and relative frequencies in a two-way table.

• Construct and interpret a two-way table summarizing data on two categorical variables collected from the same subjects.

• Use relative frequencies calculated for rows or columns to describe possible association between the two variables.

Essential Questions

• How can you use two-way tables to display relative frequencies and interpret the pattern in the table?

• How can you use relative frequencies to describe the association between two variables?

• To find relative frequency, set up a ratio comparing frequency/total. Then convert the ratio to a percentage.

• Read questions carefully to determine whether the "total" is referring to the entire table or a specific row or column.

Calculating Relative Frequency

• While frequency is the number of times that something occurs, relative frequency tells us the number of times something occurs compared to the total.

Relative Frequency

Relative Frequency

​1. In a survey of 50 people, 23 individuals answered that their favorite ice cream flavor was vanilla. What was the relative frequency of individuals who chose vanilla? Express your answer as a ratio and a percent.

2. A group of people surveyed were asked whether they have a gym membership and if they floss regularly. Complete each blank space in the two-way table.

3. Of the people surveyed, what is the relative frequency of people who floss regularly?

4. Of the people who own a gym membership, what is the relative frequency of people who floss regularly?

5. Of the people who do not own a gym membership, what is the relative frequency of people who floss regularly?

​Ratio: Percent:

​Ratio: Percent:

​Ratio: Percent:

Fill in the Blanks

3. Of the people surveyed, what is the relative frequency of people who floss regularly?

Express your answer as a ratio.

Fill in the Blanks

3. Of the people surveyed, what is the relative frequency of people who floss regularly?

Express your answer as a percent

Fill in the Blanks

4. Of the people who own a gym membership, what is the relative frequency of people who floss regularly?

Express your answer as a ratio.

Fill in the Blanks

4. Of the people who own a gym membership, what is the relative frequency of people who floss regularly?

Express your answer as a percent.

Fill in the Blanks

5. Of the people who do not own a gym membership, what is the relative frequency of people who floss regularly?

Express your answer as a ratio.

Fill in the Blanks

5. Of the people who do not own a gym membership, what is the relative frequency of people who floss regularly?

Express your answer as a percent.

Multiple Choice

6. Does there seem to be a relationship between people who own a gym membership and people who floss regularly?

• Yes

• No

Liz wanted to see if there was any association between people who have kids and people who have pets. The two-way table shows her results from a survey.

7.

Fill in the Blanks

a. Of the people surveyed, what is the relative frequency of people who have pets?

Fill in the Blanks

b. Of the people who have kids, what is the relative frequency of people who have pets?

Fill in the Blanks

c. Of the people who do not have kids, what is the relative frequency of people who have pets?

Multiple Choice

d. Does there seem to be any association between people who have kids and people who have pets?

• Yes

• No