Homework Quiz #11A
Lesson 8.2 – Relative Frequency
The Plan For Today
• Lesson 8.1 – Due Today
• HWQ #11A: 7.1, 7.2, 7.3
• Lesson 8.2
• Calculate relative frequencies
• Find possible associations from
frequency tables
• 8.2 Homework
7.1
State A, B, and C in
this Standard Form
equation.
Given the two functions
for cost in terms of hours,
for how many hours will
the cost be the same?
7.2
f ( x) = 500 x + 5000
g ( x) = 700 x + 4000
2 x + 7 y = −14
Show work
7.3 a. Write the equation of
the boundary line for
the inequality.
7.3
Graph the inequality
on the coordinate
plane.
b. Is the line solid or
dashed?
Quiz: Mod.8 & 10 – Mon. 12/7
HWQ #12 – Tues. 12/8
Lesson 8.2 – Relative Frequency
To show what portion of a data set each category
in a frequency table makes up, you can convert
the data to relative frequencies.
The relative frequency of a category is the
frequency of the category divided by the total of
all frequencies.
g ( x) <
h ( x ) ≤ −2 x − 4
1
x+2
3
5 points each
Lesson 8.2 – Relative Frequency
Two types of relative frequencies that are useful
for characterizing the data in a two-way frequency
table can be used to make up a relative frequency
table:
A 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.
A joint relative frequency is found by dividing a
frequency that is not in the Total row or the Total
column by the grand total. It tells what portion of
the total has both of the two specified
characteristics.
Lesson 8.2 – Relative Frequency
Use the two-way table of data from a student
survey to answer the following question.
What is the marginal relative frequency of students
surveyed who like weight lifting? Write the marginal
relative frequency as a percent, if necessary, round
to the nearest tenth.
Lesson 8.2 – Relative Frequency
A conditional relative frequency describes
what portion (the “relative frequency”) of a group
with a given characteristic (the “condition or
conditional statement”) also has another
characteristic of the other type.
A conditional relative frequency is found by
dividing a joint frequency (the value in a non-total
cell of a joint relative table) by the total for its row
or column (whichever row or column is the
condition).
1
Lesson 8.2 – Relative Frequency
The results of a survey of 46 students and the
foreign language they are studying are shown in the
two-way relative frequency table.
Homework
1. Go to my.hrw.com
2. Example & Step-by-Step
3. Try Another
4. Ask questions…Write up
similar example first!
5. You can do it!!
What fraction of the surveyed students are
boys taking Spanish?
What did you like?
What didn’t you like?
What did you learn?
What isn’t quite clear?
______ is awesome!
Please stop _________.
Anything else…
2