Finite Math Examples

$3$ , $8$ , $11$ , $15$ , $18$ , $21$ , $2$ , $33$ , $34$ , $36$ , $82$

Step 1

The number of classes can be estimated using the rounded output of Sturges' rule, $N = 1 + 3.322 \log (n)$ , where $N$ is the number of classes and $n$ is the number of items in the data set.

$1 + 3.322 \log (11) = 4.4595065$

Step 2

Select $4$ classes for this example.

$4$

Step 3

Find the data range by subtracting the minimum data value from the maximum data value. In this case, the data range is $82 - 2 = 80$ .

$80$

Step 4

Find the class width by dividing the data range by the desired number of groups. In this case, $\frac{80}{4} = 20$ .

$20$

Step 5

Add one to $20$ to get the size of each group.

$21$

Step 6

Start with $2$ and create $4$ groups of size $21$ .

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 2 - 22 \\ 23 - 43 \\ 44 - 64 \\ 65 - 85 \end{array}$

Step 7

Determine the class boundaries by subtracting $0.5$ from the lower class limit and by adding $0.5$ to the upper class limit.

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 2 - 22 & 1.5 - 22.5 \\ 23 - 43 & 22.5 - 43.5 \\ 44 - 64 & 43.5 - 64.5 \\ 65 - 85 & 64.5 - 85.5 \end{array}$

Step 8

Draw a tally mark next to each class for each value that is contained within that class.

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 2 - 22 & 1.5 - 22.5 & | | | | | | | \\ 23 - 43 & 22.5 - 43.5 & | | | \\ 44 - 64 & 43.5 - 64.5 \\ 65 - 85 & 64.5 - 85.5 & | \end{array}$

Step 9

Count the tally marks to determine the frequency of each class.

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 2 - 22 & 1.5 - 22.5 & 7 \\ 23 - 43 & 22.5 - 43.5 & 3 \\ 44 - 64 & 43.5 - 64.5 & 0 \\ 65 - 85 & 64.5 - 85.5 & 1 \end{array}$