Solution - Statistics

Divide the sum by the number of terms:

Sum
$$121$$
Number of terms
$$7$$

$$x̄=\frac{121}{7}=17.286$$

The mean equals $$17.286$$

Arrange the numbers in ascending order:
3,8,14,20,20,26,30

Count the number of terms:
There are (7) terms

Because there is an odd number of terms, the middle term is the median:
3,8,14,20,20,26,30

The median equals 20

To find the range, subtract the lowest value from the highest value.

The highest value equals 30
The lowest value equals 3

$$30-3=27$$

The range equals 27

To find the sample variance, find the difference between each term and the mean, square the results, add together all of the squared results, and divide the sum by the number of terms minus 1.

The mean equals 17.286

To get the squared differences, subtract the mean from each term and square the result:

To get the sample variance, add together the squared differences and divide their sum by the number of terms minus 1

Sum:
$$86.224+10.796+7.367+7.367+75.939+161.653+204.082=553.428$$
Number of terms:
$$7$$
Number of terms minus 1:
6

Variance:
$$\frac{553.428}{6}=92.238$$

The sample variance ($$s^2$$) equals 92.238

The standard deviation of the sample equals the square root of the sample variance. This is why the variance is usually represented by a squared variable.

Variance: $$s^2=92.238$$

Find the square root:
$$s=\sqrt{\left(92.238\right)}=9.604$$

The standard deviation ($$s$$) equals 9.604