# Arithmetic Mean (Mathematics Lesson)

# What Is the Arithmetic Mean?

The arithmetic mean (or*mean average*or just

*average*) is the sum of all numbers divided by the total amount of numbers.

# How to Find the Arithmetic Mean

Question: What is the average of 86, 99, 98, 54, 35, and 48?Step 1

(86 + 99 + 98 + 54 + 35 + 48 = 420).

Step 2

(There are 6 in this set.)

Step 3

(420/6 = 70). The arithmetic mean is 70.

##### Interactive Test

**show**

##### Note

# ARITHMETIC MEAN IS THE MOST COMMON TYPE OF AVERAGE

The arithmetic mean is the most common average, and it’s the one that people will think you’re talking about if you don’t specify which average you’re using.(NB: It is more commonly called the mean average.)

# A WEAKNESS OF THE ARITHMETIC MEAN

The arithmetic mean is useful when a central tendency or middle figure is needed, but its weakness is that is can be badly skewed by outliers. For example, it would be useful in measuring the average salary of a group of metal workers in a factory, but it would be less useful in measuring the average salary of everyone in the factory, because the factory owner’s and executives’ salaries would skew the arithmetic mean. As a result, a senior but non-exectutive manager could find himself on a "below average" wage.# DISCUSSION POINT

Did you know that half the doctors in the world are below average?(NB: They are compared to the other half of doctors but not compared to the rest of the population.)