# What is arithmetic mean ? Definition and examples.

The arithmetic mean of a set of numbers, also called mean, is the sum of the set of numbers divided by the number of numbers in the set.

Example #1

Sylvia's scores on 5 math tests are 80, 75, 90, 100, and 60. What is the arithmetic mean?

The set of scores is 80, 75, 90, 100, and 60.

The sum of the set of scores is 80 + 75 + 90 + 100 + 60 = 405

The number of numbers is 5

The arithmetic mean is equal to 405 / 5 = 81

Example #2

Gas prices at 6 different gas stations are 2.60, 2.45, 2.70, 2.70, 2.50, and 2.40. What is the arithmetic mean?

The set of gas prices is 2.60, 2.45, 2.70, 2.70, 2.50, and 2.40

The sum of the set of gas prices is  2.45 + 2.70 + 2.70 + 2.50 + 2.40 = 15.35

The number of numbers is 6

The arithmetic mean is equal to 15.35 / 6 = 2.56

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