Finite Math Examples

$\begin{array}{c} Class & Frequency \\ 90 - 99 & 4 \\ 80 - 89 & 6 \\ 70 - 79 & 4 \\ 60 - 69 & 3 \\ 50 - 59 & 2 \\ 40 - 49 & 1 \end{array}$

Step 1

Reorder the classes with their related frequencies in an ascending order (lowest number to highest), which is the most common.

$\begin{array}{c} Class & Frequency (f) \\ 40 - 49 & 1 \\ 50 - 59 & 2 \\ 60 - 69 & 3 \\ 70 - 79 & 4 \\ 80 - 89 & 6 \\ 90 - 99 & 4 \end{array}$

Step 2

The lower limit for every class is the smallest value in that class. On the other hand, the upper limit for every class is the greatest value in that class.

$\begin{array}{c} Class & Frequency (f) & Lower Limits & Upper Limits \\ 40 - 49 & 1 & 40 & 49 \\ 50 - 59 & 2 & 50 & 59 \\ 60 - 69 & 3 & 60 & 69 \\ 70 - 79 & 4 & 70 & 79 \\ 80 - 89 & 6 & 80 & 89 \\ 90 - 99 & 4 & 90 & 99 \end{array}$

Step 3

Class boundaries are the numbers used to separate classes. The size of the gap between classes is the difference between the upper class limit of one class and the lower class limit of the next class. In this case, $gap = 50 - 49 = 1$ .

$gap = 1$

Step 4

The lower boundary of each class is calculated by subtracting half of the gap value $\frac{1}{2} = 0.5$ from the class lower limit. On the other hand, the upper boundary of each class is calculated by adding half of the gap value $\frac{1}{2} = 0.5$ to the class upper limit.

$\begin{array}{c} Class & Frequency (f) & Lower Limits & Lower Boundaries & Upper Limits & Upper Boundaries \\ 40 - 49 & 1 & 40 & 40 - 0.5 & 49 & 49 + 0.5 \\ 50 - 59 & 2 & 50 & 50 - 0.5 & 59 & 59 + 0.5 \\ 60 - 69 & 3 & 60 & 60 - 0.5 & 69 & 69 + 0.5 \\ 70 - 79 & 4 & 70 & 70 - 0.5 & 79 & 79 + 0.5 \\ 80 - 89 & 6 & 80 & 80 - 0.5 & 89 & 89 + 0.5 \\ 90 - 99 & 4 & 90 & 90 - 0.5 & 99 & 99 + 0.5 \end{array}$

Step 5

Simplify the lower and upper boundaries columns.

$\begin{array}{c} Class & Frequency (f) & Lower Limits & Lower Boundaries & Upper Limits & Upper Boundaries \\ 40 - 49 & 1 & 40 & 39.5 & 49 & 49.5 \\ 50 - 59 & 2 & 50 & 49.5 & 59 & 59.5 \\ 60 - 69 & 3 & 60 & 59.5 & 69 & 69.5 \\ 70 - 79 & 4 & 70 & 69.5 & 79 & 79.5 \\ 80 - 89 & 6 & 80 & 79.5 & 89 & 89.5 \\ 90 - 99 & 4 & 90 & 89.5 & 99 & 99.5 \end{array}$

Step 6

Add the lower and upper class boundaries columns to the original table.

$\begin{array}{c} Class & Frequency (f) & Lower Boundaries & Upper Boundaries \\ 40 - 49 & 1 & 39.5 & 49.5 \\ 50 - 59 & 2 & 49.5 & 59.5 \\ 60 - 69 & 3 & 59.5 & 69.5 \\ 70 - 79 & 4 & 69.5 & 79.5 \\ 80 - 89 & 6 & 79.5 & 89.5 \\ 90 - 99 & 4 & 89.5 & 99.5 \end{array}$