Arithmetic Mean

Arithmetic Mean: Definition, Formula & Examples

arithmetic mean definition

What is Arithmetic Mean?

The arithmetic mean, commonly referred to as simply the “mean” or “average”, is a fundamental concept in statistics and probability theory. This mathematical principle helps in finding the central value of a data set, and is often used to summarize numerical data providing a single, representative figure. Whether you realize it or not, arithmetic mean permeates daily life, from calculating grade point averages in school to assessing economic data or tracking sports statistics.

Key Points
  1. The arithmetic mean, also known as the average, is a commonly used measure of central tendency.
  2. It is calculated by summing up all the values in a data set and dividing by the total number of values.
  3. It is influenced by extreme values, which can skew the result.

Understanding the Arithmetic Mean

The arithmetic mean is a measure of central tendency, which provides a way to summarize a set of numbers with a single representative value. It is calculated by adding up all the numbers in a data set and then dividing by the count of those numbers. For example, if we want to find the mean of 2, 4, and 6, we would add those numbers together to get 12, and then divide by 3 (since there are three numbers in the set) to get a mean of 4.

In mathematical notation, the arithmetic mean of a set of numbers is often denoted by the Greek letter μ (mu) or simply as ‘x̄’ (x-bar) when referring to a sample mean. Given ‘n’ numbers (x1, x2, x3, …, xn), the arithmetic mean (μ) can be calculated as:

μ = (x1 + x2 + x3 + … + xn) / n

It is perhaps the most commonly used type of average. It’s the type of average that is most intuitive to understand and compute. In many contexts, when people refer to the “average,” they are usually referring to the arithmetic mean.

It’s important to note, however, that while it is a useful and versatile tool, it isn’t always the best measure of central tendency for every set of numbers. It can be greatly affected by outliers, or numbers that are much larger or smaller than the others in the data set. These extreme values can distort the mean, making it less representative of the data as a whole. Other measures of central tendency, such as the median or mode, might be more appropriate in these cases.

Uses of Arithmetic Mean

The arithmetic mean is one of the most widely used measures of central tendency in fields like statistics, mathematics, economics, and social sciences. Below are some of its common uses:

  1. Data Analysis The arithmetic mean is used in basic data analysis across various fields. For instance, in business, it is used to calculate average sales, average cost, average revenue, etc.
  2. Comparative Studies It is a vital tool in comparative statistical studies, such as comparing the average income of two different groups of people, or comparing the average productivity of two different factories.
  3. Economics In economics, the arithmetic mean is used to calculate key economic indicators like per capita income, which is the average income of individuals in a country. It’s also used to calculate the average growth rate of a country’s GDP.
  4. Research In various types of research, the arithmetic mean is used to summarize numerical data, providing a single representative figure for comparison. For example, it can be used in medicine to determine the average effect of a drug in clinical trials.
  5. Sports Statistics In sports, the arithmetic mean is used to calculate average statistics like batting averages in cricket or baseball, shooting percentages in basketball, or pass completion rates in football.
  6. Quality Control In manufacturing, it is used in quality control processes to monitor the average quality of products being produced.

It’s important to remember that while the arithmetic mean is highly versatile, it isn’t always the best measure to use. In some cases, other measures like median or mode may be more appropriate. Particularly, the arithmetic mean is sensitive to extreme values or outliers, which can distort the mean, making it less representative of the data as a whole. In such cases, the median might provide a better representation of the central tendency of the data set.

Formula of Arithmetic Mean

The arithmetic mean, often simply referred to as the ‘mean’, of a set of values is calculated using the following formula:

  1. Add up all the numbers in the data set.
  2. Divide the sum by the total number of values.

In mathematical notation, if you have a data set consisting of ‘n’ numbers represented by x₁, x₂, …, xₙ, the arithmetic mean (denoted as μ) is calculated as follows:

μ = (x₁ + x₂ + … + xₙ) / n

For example, if you have five test scores: 85, 90, 78, 92, and 88, the arithmetic mean would be calculated as follows:

μ = (85 + 90 + 78 + 92 + 88) / 5 = 86.6

Therefore, the arithmetic mean of the test scores is 86.6. This indicates that on average, the test scores fall around the 86.6 mark.

Types of Arithmetic Mean

Arithmetic mean can be classified into three main types, based on the data set with which it is associated:

  1. Simple This is the most commonly used type of mean. It is used when all the observations in a data set are of equal importance. The formula is as stated earlier, i.e., the sum of all observations divided by the number of observations.
  2. Weighted This type of mean is used when the importance of all observations is not the same, i.e., some observations carry more weight than others. The weighted arithmetic mean is the sum of the product of each observation and its corresponding weight, divided by the sum of the weights.
  3. Grouped This is used when data is grouped into different categories or classes. In this case, the mid-points of each class are taken as x-values and the frequencies of each class are considered as weights. The formula is the same as that of the weighted arithmetic mean, but with frequencies acting as weights.

Each type of arithmetic mean is applicable in different scenarios and are used as per the requirement of the data analysis.

Advantages of Arithmetic Mean

1. Easy to Understand and Compute

The concept of arithmetic mean is straightforward and easy to grasp. Calculations involving the arithmetic mean are simple to perform, making it a popular choice for a wide range of applications.

2. Considers Every Data Point

The arithmetic mean accounts for every value in the data set, which makes it a comprehensive measure of central tendency. This is in contrast to other measures like median and mode, which do not take into account every individual data point.

3. Basis for Further Statistical Analysis

The arithmetic mean is fundamental to numerous other statistical measures and procedures, such as variance and standard deviation. Without the mean, these calculations would not be possible.

4. Unique Value

For any given data set, there is only one arithmetic mean. This characteristic makes it a reliable and unambiguous measure of central tendency.

5. Can be Used in Further Mathematical Operations

Unlike other measures of central tendency like median or mode, arithmetic mean can be easily used for further algebraic calculations, making it highly convenient and versatile in data analysis.

Disadvantages of Arithmetic Mean

1. Sensitive to Extreme Values

One of the main disadvantages of the arithmetic mean is that it is sensitive to extreme values, or outliers, in the data set. A single extremely large or small value can distort the mean, making it an inaccurate representation of the data.

2. Not Applicable to All Data Types

The arithmetic mean can only be calculated for quantitative (interval or ratio) data. It cannot be used for nominal or ordinal data, which are categorized or ranked respectively.

3. Doesn’t Reflect Data Distribution

While the arithmetic mean gives a measure of the central tendency, it does not provide any insight into how the data is distributed. Two data sets may have the same mean but be distributed very differently.

4. Can Mislead Interpretations

If the data is skewed or has outliers, the mean can give a misleading picture of the central tendency. This could lead to inaccurate interpretations and conclusions.

5. Not Always the Most Appropriate Measure

In certain situations, other measures of central tendency, such as the median or mode, might be more appropriate. For instance, when considering income data, which is often skewed, the median (middle income) might offer a more representative measure than the mean.

Examples of Arithmetic Mean

1. Exam Scores

Let’s say a student scores 85, 90, 92, 88, and 95 on their five exams in a semester. The arithmetic mean of these scores can be calculated as (85+90+92+88+95)/5 = 90. This mean score of 90 provides a general idea of the student’s academic performance.

2. House Prices

Consider the prices of five houses in a neighborhood: $200,000, $225,000, $275,000, $300,000, and $325,000. The arithmetic mean would be ($200,000+$225,000+$275,000+$300,000+$325,000)/5 = $265,000. This gives you an average house price in that neighborhood.

3. Average Daily Temperature

If you’re looking at the average daily temperature over a week, and the temperatures are 22°C, 24°C, 25°C, 23°C, 27°C, 24°C, and 26°C, then the arithmetic mean is (22+24+25+23+27+24+26)/7 = 24.71°C. This gives you an idea of the average temperature for that week.

4. Company Earnings

A company earns $5,000, $7,000, $6,000, $8,000, and $7,500 in profit over five consecutive quarters. The arithmetic mean of these profits is ($5,000+$7,000+$6,000+$8,000+$7,500)/5 = $6,700. This represents the average quarterly profit of the company.


What is the arithmetic mean?

The arithmetic mean, also called the average, is a measure of central tendency that represents the typical value of a set of numbers.

How is the arithmetic mean calculated?

To calculate the arithmetic mean, add up all the numbers in a set and divide the sum by the total count of numbers.

What is the significance of the arithmetic mean?

The arithmetic mean is widely used in statistics and research to summarize data and provide a representative value that can be used for comparisons and analysis.

Can the arithmetic mean be affected by extreme values?

Yes, the arithmetic mean can be influenced by extreme values, leading to a potential distortion of the average. It is important to consider other measures of central tendency, such as the median, in such cases.

About Paul

Paul Boyce is an economics editor with over 10 years experience in the industry. Currently working as a consultant within the financial services sector, Paul is the CEO and chief editor of BoyceWire. He has written publications for FEE, the Mises Institute, and many others.

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