Graphing Data
Please use the class data to:
Find the median, mode, mean and range
Create the following charts and graphs:
Frequency Table:
A frequency table is a way to show how often an item or number
occurs.
Interval
Tally
Frequency
1-5
||||
4
6-10
|||| |||
8
11-15
||||
4
16-20
||
2
The steps are:
1. Choose a range that includes all the data.
2. Divide that range into equal intervals.
3. Count the number of data points in each interval.
Histograms
Once you have a frequency table, you can use it to make the
histogram. Making a histogram is just like making a bar graph, except
that each bar represents an interval and there are no spaces between
the bars and no gaps in the numbers.
Number of weeks as a top seller
10
8
6
4
2
1-5
6-10
11-15
16-20
Probability and Statistics for Teachers
Stem and Leaf Plot
To make a stem and leaf plot:
1. Title your lot.
2. Write the data in order from least to greatest.
3. Find the least and the greatest values.
4. Choose stem values that will include the extreme values.
Write the tens vertically from least to greatest. Draw a vertical line
to the right of the stem values.
6. Separate each number into stems (tens) and leaves (ones). Write
each leaf to the right of its stem in order from least to greatest.
7. Write a key that explains how to read the stems and leaves.
Stem Leaves
0
1, 3,4 ,5 ,6 ,6, 6, 7, 7, 8, 8, 9
1
1, 4, 5, 5, 7
2
0
Box and Whiskers Plot
To make a box and whisker plot:
1. Write the data in order from least to greatest.
2. Draw a number line that can show the data in equal intervals.
3. Mark the median.
4. Mark the median of the upper half of the numbers (the upper
quartile).
4. Mark the median of the lower half (the lower quartile).
6. Mark the upper extreme (the greatest number).
7. Mark the lower extreme (the lowest number).
8. Draw a box between the lower quartile and the upper quartile.
Split the box by drawing a vertical line through the median. Draw two
“whiskers” from the quartiles to the extremes.
12
13
14
Lower extreme
Lower
Quartile
15
16
Median
17
18
Upper
Quartile
Probability and Statistics for Teachers
19
20
Upper extreme