Constructing Graphs

Making a Line Plot• Collect data and put in chronological order

• Determine a scale and intervals• If you have a small range, you should probably use intervals of 1

• With larger scales, it is best to mark intervals every 2, 5, or 10 numbers.

Ex. Scores on a math test

63 68 72 74 79 80 80 83 84 84 84

85 88 90 90 90 90 93 95 95 95 97

Making a Line Plot

• Draw a horizontal line and mark the intervals.

60 65 70 75 80 85 90 95 100

Ex. Scores on a math test

63 68 72 74 79 80 80 83 84 84 84

85 88 90 90 90 90 93 95 95 95 97

Making a Line Plot• Mark an X above the number for each data point.• If a number is repeated, place one X above the

other.

X X X X X XX

X X X X

X X XXXX

X XX

X

Ex. Scores on a math test

63 68 72 74 79 80 80 83 84 84 84

85 88 90 90 90 90 93 95 95 95 97

60 65 70 75 80 85 90 95 100

Making a Line Plot• Count the number of data points and count the

number of X’s to make sure you plotted each point!

Ex. Scores on a math test

63 68 72 74 79 80 80 83 84 84 84

85 88 90 90 90 90 93 95 95 95 97

X X X X X XX

X X X X

X X XXXX

X XX

X

60 65 70 75 80 85 90 95 100

You Try!• There are 31 days in August, and here are the

temperatures for that month:

August 69 70 71 71 72 72 72 73 74 75 75 76 76 76 77 77 77 77 77 78 78 80 81 82 82 83 83 85 85 90 93

X X X X X X X X X

X X X

65 70 75 80 85 90 95

X X

X X X

X XX X

X

X X X X X

X X X

X

Here are one student’s math test scores. Make a stem-and-leaf plot for this data.

First, draw the dividing lines.

Here are one student’s math test scores. Make a stem-and-leaf plot for this data.

Next, label the stem side and the leaf side.

Stems Leaves

Find the smallest piece of data and plot it on the grid.

7 5

Here are one student’s math test scores. Make a stem-and-leaf plot for this data.

Stems Leaves

Find the next smallest piece of data and plot it on the grid.

9

The 7 for the tens place is already there. We just add the 9.

Here are one student’s math test scores. Make a stem-and-leaf plot for this data.

7 5 Stems Leaves

7 5 9 Stems Leaves

Continue with this process until you have entered all the data.

8 3 4 6 6 8 9 1 4 9

7 5 9 Stems Leaves

8 3 4 6 6 8 9 1 4 9

Remember to add a title.

Test Scores

7 5 9 Stems Leaves

8 3 4 6 6 8 9 1 4 9

Test Scores

Don’t forget the key!

Key: 7 5 means 75

You Try!• There are 31 days in August, and here are the

temperatures for that month: August 69 70 71 71 72 72 72 73 74 75 75 76 76 76 77 77 77 77 77 78 78 80 81 82 82 83 83 85 85 90 93

6 9 7 0 1 1 2 2 2 3 4 5 5 6 6 6 7 7 7 7 7 8 8 8 0 1 2 2 3 3 5 5 9 0 3

Stems Leaves

Temperatures for August

Key: 7 | 6 = 76 degrees Fahrenheit

Step 1 – Order Numbers

1. Order the set of numbers from least to greatest

2. Find the median. The median is the middle number. If the data has two middle numbers, find the mean of the two numbers. What is the median?

Step 2 – Find the Median

3. Find the lower and upper quartiles. These are the middle numbers on each side of the median. What are they?

Step 3 – Upper & Lower Quartiles

Now you are ready to construct the actual box & whisker graph. First you will need to draw an ordinary number line that extends far enough in both directions to include all the numbers in your data:

Step 4 – Draw a Number Line

Locate the main median 12 using a vertical line just above your number line:

Step 5 – Draw the Parts

Step 5 – Draw the PartsLocate the lower quartile (8.5) and the upper quartile (14) with similar vertical

lines:

Step 5 – Draw the PartsNext, draw a box using the lower and

upper quartile lines as endpoints:

Finally, the whiskers extend out to the data's smallest number 5 and largest

number 20:

Step 5 – Draw the Parts

1 23

54

Median Upper QuartileLower Quartile

Lower Extreme Upper Extreme

Step 6 - Label the Parts of a Box-and-Whisker Plot

You Try!• There are 31 days in August, and here are the

temperatures for that month:

August 69 70 71 71 72 72 72 73 74 75 75 76 76 76 77 77 77 77 77 78 78 80 81 82 82 83 83 85 85 90 93

Practice: Constructing Graphs Worksheet