Do Now
Last Season, there were 26 students on the
Springfield high school varsity football team, all
freshman, sophomores, juniors, and seniors.
1. 18 students are seniors. What percent of the team
are seniors?
2. 19% of the team are juniors. How many players
are juniors?
3. Freshman and sophomores together, make up
what percent of the team?
Objective
SWBAT analyze a frequency table, and relative
frequency table.
SWBAT analyze and interpret pie charts and bar
graphs.
Frequency Table
A frequency table is a table that lists
items and uses tally marks to record and
show the number of times they occur.
We record
totals and
category
names.
Frequency Table
•While counts are useful, statistians
usually want to know the proportion.
•To calculate the proportion, take the
count and divide by the total.
•Multiply this number by 100 to
express the proportion as a percent.
Frequency Table
•Relative frequency tables display the data
using the calculated percentages from our
proportions.
•Frequency tables and relative frequency,
both show the distribution.
Example 1: Counts to Proportions
What percentage of people were in each class of the titanic?
Class
Count
Percentage
First
325
15%
Second
285
Third
706
Crew
885
Bar Chart
A bar chart displays the distribution of
a categorical variable, and shows the
count for each category.
A relative frequency bar chart displays
the percentage of each category.
Example 2: Interpreting Bar Graphs
Here is a bar chart
summarizing the
frequency of visitors to The
Children’s Hospital of
Philadelphia (CHOP).
a)Which frequency was
most common?
b)Is it easier to see as a bar
chart or pie chart?
You try! Example 3
Here is a bar chart
summarizing the most
used technology in 2009.
a) Which is the least
common rating? b) A New
York Times article claimed
that there had been a
growth of Ipod use at the
expense of radio. The
writer referred to the bar
chart as evidence. Does
the bar chart support his
claim?
Pie Charts
Pie Charts show the whole group of cases as a
circle. They slice the circle into pieces whose
sizes are proportional to the fraction of the
whole in each contingency.
Example 5
The circle graph below shows the percentage of the staff budget that
was allocated to salaries for each department for a company last year.
The company is expecting to
have $1,500,000 in the budget
for salaries this year. Using
the graph, predict the amount
of money that will be
allocated to the accounting
department's salaries this
year. Also determine the least
common allocation of the
budget.
The pie chart gives information about the bills paid by a Water Company.
(a) If the Water Company spent $18 000 on Materials, work out the amount
it spent on Rates.
(b) Which expense is least common?
Example 6
Independent Practice
Pg 39 Numbers 1-8
During this time, there is no talking
Exit Ticket
Here is a bar chart summarizing
the favorite fruits of 145
students at Sankofa Freedom
Academy CS
1) Which is the least common
rating?
2) Is it easier to explain as a pie
chart or bar chart?
Liberation Work
Complete the hand out distributed at the end of class.