Statistics

Statistics

Now we have a completed plot. Remember, like stems can be combined. Look at 165, 166, and 167. In the stem-and-leaf plot, it is written as 16 for the stem with 5, 6, and 7 for the leaf. This will give us 165, 166, and 167. Let us look at a slightly different data set. You are given the exam grades for the statistics class: 88, 88, 82, 93, 94, 94, 94, 99, 100, 71.

First, put the data in order: 71, 82, 88, 88, 93, 94, 94, 99, 100

Now you are asked to represent this data using a stem-to-leaf plot. Remember our rules; the leaf is only a single value which is the last digit in the number and every number must be represented.

7 1

8 2 8 8

9 3 4 4 9

10 0 From the example above, we had two 88s on the exam. Therefore, our stem-and-leaf plot will have two 8s in the leaf portion. Likewise, we have two 94s on the exam and our leaf portion has two 4s after the value 9.

During your exam, you may be given a stem-and-leaf plot and be asked to determine the mean, median, mode, and range. For this example; you are given the following stem-and-leaf plot and you are asked to determine the mean.

5 0 1 1 2

6 6

7 3 4 4 9

8 0 The 1st step is to write out the data set. For this, the stem goes with each of the leaf values.

50, 51, 51, 52, 66, 73, 74, 74, 79, 80.

Now we can calculate the mean, this concept was covered in Chapter 1, by adding the sum of the values and dividing by 10.

Our mean is 50+51+51+52+66+73+74+74+79+80 / 10 = 65

*Can you determine the median, mode and range? Be sure to revisit concepts in Chapter 1. Remember a stem-and-leaf plot use the entire data set; it is best used for smaller data sets.

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