MJ2

Ch 2.7 – Bar Graphs & Histograms

Bellwork Please take out your

homework from yesterday and leave it on your desk for me to check

Analyze the pie chart. Identify the error(s)

Student Favorite

Ice Cream Flavor

Number of

Students Surveyed

Vanilla 52

Chocolate 37

Strawberry

23

Vanilla

Chocolate

Strawberry

52%37%

23 %

Assignment Review

Text p. 420 # 5 & 6; p. 421 # 12-14

Before we begin… Please take out your notebook and get

ready to work… Today we will discuss bar charts and

histograms which, are two more tools that can help you organize and interpret data…

It is expected that you already know how to construct these types of charts…so this should be a quick review

Objective

Students will construct and interpret bar charts and histograms

Comparison

Raise your hand if you already know the difference between a bar chart and a histogram…

Difference A bar chart is a method of comparing data by

using bars to represent quantities A histogram is a special type of bar chart.

The histogram uses bars to represent frequencies of numerical data that have been organized in intervals

Essentially, in a bar chart each of the bars is separated by a space. In a histogram the bars are connected and represent ranges of numbers

Constructing a Bar Chart To construct a bar chart

Draw a horizontal & vertical axis. Label the axes. Depending upon how

you label the axes the bars will be horizontal or vertical

Add a title – Note: All charts are required to have a title identifying what the data represents.

Lets see what that looks like…

Example Using the data

from the table construct a bar chart

Demonstrate on Board

Animal Speed

Cheetah 70

Wildebeest

50

Lion 50

Elk 45

Zebra 40

Interpreting the Data

The bar chart provides a quick visual of the data…

From the bar chart we can Identify which animal is fastest… Identify animals that run at the same

maximum speed… Identify the slowest animal of the

groups represented…

Constructing a Histogram To construct a Histogram

Draw a horizontal & vertical axis. Label the axes. Depending upon how you label

the axes the bars will be horizontal or vertical Draw a bar to represent the frequency of each

interval – Note: There should be no space between the bars

Add a title – Note: All charts are required to have a title identifying what the data represents.

Lets see what that looks like…

Example The number of wins

for the 29 teams of the NBA have been organized into a frequency table

Construct a Histogram

Demonstrate on Board

Number of

Wins

Frequency

11 – 20 3

21 – 30 4

31 – 40 4

41 – 50 10

51 – 60 8

Interpreting the Data The histogram provides a visual of

the data… From the histogram we can

Identify the range of the highest winners See that most teams had between 41 –

60 wins Identify least number of wins However, we can not identify the

individual team with the most wins…

Summary

In the notes section of your notebook summarize the key concepts covered in today’s lesson

Today we discussed Bar Charts & Histograms What is the difference between the two?

Classwork

Ch 2 Resource Book p. 99 Lesson 2.7 Word problems…

This is an individual assignment that is due at the end of class…

Read the directions before you begin…

Assignment

Workbook – Lesson 2.7 Pg. ____# 1 – 6