Today in class…

1. Making Frequency Tables,2. Making Histograms, 3. Analyzing Graphs, &4. Distinguishing between Bar Graphs & Histograms

Making Frequency Tables

Making a FREQUENCY Table

The list shows the ages of 25 persons selected at random from the audience of a recent showing of a comedy movie. Make a frequency table of the ages using intervals 17–24, 25–32, 33–40, 41–48, and 49–56. What is the most common interval of attendance ages?

Explore You have a list of ages. You need to know how many ages fall into each interval.

Making a FREQUENCY Table

Plan Make a table to show the frequency, or number, of ages in each interval.

Solve The row with the greatest frequency is the row for ages 17–24, so this is the most common interval of attendance ages.

Making a FREQUENCY Table

Check Make sure the frequency table includes each age from the list.

Answer: The greatest frequency is for ages 17–24, so this is the most common interval of attendance ages.

A. AB. BC. CD. D

A. baseball

B. football

C. soccer

D. volleyball

The list shows the favorite sports of 25 people selected at random. In the list, S represents soccer, B represents baseball, F represents football, and V represents volleyball.

Make a frequency table of the favorite sports. What is the most popular sport?

Frequency Table Using Letters

Frequency Table

Favorite Sports of PeopleType Of Sport Tally Frequency

Baseball I I I I I 5

Football I I I I I I 6

Volleyball I I I I I I 6

Soccer I I I I I I I I 8

Which type of sport is most popular?

Your Turn

• Make a Frequency Table• Make a Histogram

Histogram

• Uses bars to represent the frequency of numerical data that have been organized into intervals.

Construct a Histogram

FOOD The list below shows the number of grams of caffeine in certain types of tea. Use intervals 1–20, 21–40, 41–60, 61–80, and 81–100 to make a frequency table. Then construct a histogram.

Construct a Histogram

Place a tally mark for each value in the appropriate interval. Then add up the tally marks to find the frequency for each interval.

To construct a histogram, follow these steps.

Step 1 Draw and label a horizontal and vertical axis. Include a title.Step 2 Show the intervals from the frequency table on the horizontal

axis.

Construct a Histogram

Step 3 For each caffeine interval, draw a bar whoseheight is given by the frequency.

Answer:

FOOD The frequency table below shows the amount of caffeine in certain drinks. Draw a histogram to represent the data.

Answer:

Practice: Analyzing Graphs

Analyze and Interpret Data

WEATHER How many months had 6 or more days of rain?

Three months had 6 to 7 days of rain, and one month had 8 to 9 days of rain.

Answer: Therefore, 3 + 1 or 4 months had 6 or more days of rain.

1. A2. B3. C4. D

A. 2 months

B. 3 months

C. 4 months

D. 5 months

WEATHER How many months had 6 or more days of snow?

Analyze and Interpret Data

WEATHER How many months had exactly 2 days of rain?

Answer: This cannot be determined from the data presented in this graph. The histogram indicates that there were 3 months that had 2 or 3 days of rain, but it is impossible to tell how many months had exactly 2 days of rain.

1. A2. B3. C4. D

A. 1 month

B. 2 months

C. 6 months

D. cannot be determined

WEATHER How many months had exactly 6 days of snow?

Difference Between A Histogram & Bar Graph?

Bar Graph Histogram

Are drawn with spaces between the columns

No space between the columns (Equal intervals across the x-axis)

Qualitative (with words) or Categorical (Generally)

Quantitative (with numbers)

Ahhhhhh! How will I know it when I see it?

Example: Histogram

Example: Histogram

Example: Bar Graph

Example: Bar Graph

Example: Bar Graph

Side-by-Side