**Measures of central tendency and variability**

**Reminders**:

n: Count how many numbers there are

Mean: Add the numbers and divide by n

Degrees of freedom (df) (for variance): n-1

Variance:

- Subtract the mean from each number
- Square the answer
- Sum the squares
- Divide by the degrees of freedom

Standard deviation (s): find the square root of the variance

**For each data set, find: n, mean, df, variance and
standard deviation**

Data 1: 10, 5, 7, 8, 3

Data 2: 25, 45, 80, 65, 73, 88, 91, 100

Data 3: 133, 145, 188, 215, 225, 250, 168, 212, 127