Statistics Examples

$32$ , $15$ , $27$ , $18$ , $16$ , $24$ , $36$ , $21$ , $42$ , $32$ , $46$ , $15$ , $17$ , $38$ , $42$ , $15$ , $24$ , $37$ , $23$ , $56$ , $17$ , $36$ , $n = 8$

Step 1

Find the data range by subtracting the minimum data value from the maximum data value. In this case, the data range is $56 - 15 = 41$ .

$41$

Step 2

Find the class width by dividing the data range by the desired number of groups. In this case, $\frac{41}{8} = 5.125$ .

$5.125$

Step 3

Round $5.125$ up to the nearest whole number. This will be the size of each group.

$6$

Step 4

Start with $15$ and create $8$ groups of size $6$ .

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 15 - 20 \\ 21 - 26 \\ 27 - 32 \\ 33 - 38 \\ 39 - 44 \\ 45 - 50 \\ 51 - 56 \\ 57 - 62 \end{array}$

Step 5

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

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 15 - 20 & 14.5 - 20.5 \\ 21 - 26 & 20.5 - 26.5 \\ 27 - 32 & 26.5 - 32.5 \\ 33 - 38 & 32.5 - 38.5 \\ 39 - 44 & 38.5 - 44.5 \\ 45 - 50 & 44.5 - 50.5 \\ 51 - 56 & 50.5 - 56.5 \\ 57 - 62 & 56.5 - 62.5 \end{array}$

Step 6

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

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 15 - 20 & 14.5 - 20.5 & | | | | | | | \\ 21 - 26 & 20.5 - 26.5 & | | | | \\ 27 - 32 & 26.5 - 32.5 & | | | \\ 33 - 38 & 32.5 - 38.5 & | | | | \\ 39 - 44 & 38.5 - 44.5 & | | \\ 45 - 50 & 44.5 - 50.5 & | \\ 51 - 56 & 50.5 - 56.5 & | \\ 57 - 62 & 56.5 - 62.5 \end{array}$

Step 7

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

$\begin{array}{c} Class & Class Boundaries & Frequency \\ 15 - 20 & 14.5 - 20.5 & 7 \\ 21 - 26 & 20.5 - 26.5 & 4 \\ 27 - 32 & 26.5 - 32.5 & 3 \\ 33 - 38 & 32.5 - 38.5 & 4 \\ 39 - 44 & 38.5 - 44.5 & 2 \\ 45 - 50 & 44.5 - 50.5 & 1 \\ 51 - 56 & 50.5 - 56.5 & 1 \\ 57 - 62 & 56.5 - 62.5 & 0 \end{array}$