Pre-Algebra Examples

$16$ , $13$ , $15$ , $6$ , $21$ , $20$ , $12$ , $9$ , $12$

Step 1

The mean of a set of numbers is the sum divided by the number of terms.

$\frac{16 + 13 + 15 + 6 + 21 + 20 + 12 + 9 + 12}{9}$

Step 2

Simplify the numerator.

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Step 2.1

Add $16$ and $13$ .

$\frac{29 + 15 + 6 + 21 + 20 + 12 + 9 + 12}{9}$

Step 2.2

Add $29$ and $15$ .

$\frac{44 + 6 + 21 + 20 + 12 + 9 + 12}{9}$

Step 2.3

Add $44$ and $6$ .

$\frac{50 + 21 + 20 + 12 + 9 + 12}{9}$

Step 2.4

Add $50$ and $21$ .

$\frac{71 + 20 + 12 + 9 + 12}{9}$

Step 2.5

Add $71$ and $20$ .

$\frac{91 + 12 + 9 + 12}{9}$

Step 2.6

Add $91$ and $12$ .

$\frac{103 + 9 + 12}{9}$

Step 2.7

Add $103$ and $9$ .

$\frac{112 + 12}{9}$

Step 2.8

Add $112$ and $12$ .

$\frac{124}{9}$

Step 3

Divide.

$13.\overline{7}$

Step 4

The mean should be rounded to one more decimal place than the original data. If the original data were mixed, round to one decimal place more than the least precise.

$13.8$