Pre-Algebra Examples

$78$ , $79$ , $80$ , $80$ , $89$ , $89$ , $92$ , $93$ , $94$ , $95$ , $95$ , $95$

Step 1

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

$\frac{78 + 79 + 80 + 80 + 89 + 89 + 92 + 93 + 94 + 95 + 95 + 95}{12}$

Step 2

Simplify the numerator.

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Step 2.1

Add $78$ and $79$ .

$\frac{157 + 80 + 80 + 89 + 89 + 92 + 93 + 94 + 95 + 95 + 95}{12}$

Step 2.2

Add $157$ and $80$ .

$\frac{237 + 80 + 89 + 89 + 92 + 93 + 94 + 95 + 95 + 95}{12}$

Step 2.3

Add $237$ and $80$ .

$\frac{317 + 89 + 89 + 92 + 93 + 94 + 95 + 95 + 95}{12}$

Step 2.4

Add $317$ and $89$ .

$\frac{406 + 89 + 92 + 93 + 94 + 95 + 95 + 95}{12}$

Step 2.5

Add $406$ and $89$ .

$\frac{495 + 92 + 93 + 94 + 95 + 95 + 95}{12}$

Step 2.6

Add $495$ and $92$ .

$\frac{587 + 93 + 94 + 95 + 95 + 95}{12}$

Step 2.7

Add $587$ and $93$ .

$\frac{680 + 94 + 95 + 95 + 95}{12}$

Step 2.8

Add $680$ and $94$ .

$\frac{774 + 95 + 95 + 95}{12}$

Step 2.9

Add $774$ and $95$ .

$\frac{869 + 95 + 95}{12}$

Step 2.10

Add $869$ and $95$ .

$\frac{964 + 95}{12}$

Step 2.11

Add $964$ and $95$ .

$\frac{1059}{12}$

Step 3

Cancel the common factor of $1059$ and $12$ .

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Step 3.1

Factor $3$ out of $1059$ .

$\frac{3 (353)}{12}$

Step 3.2

Cancel the common factors.

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Step 3.2.1

Factor $3$ out of $12$ .

$\frac{3 \cdot 353}{3 \cdot 4}$

Step 3.2.2

Cancel the common factor.

$\frac{3 \cdot 353}{3 \cdot 4}$

Step 3.2.3

Rewrite the expression.

$\frac{353}{4}$

Step 4

Divide.

$88.25$

Step 5

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.

$88.3$