Last updated on June 4th, 2025
Geometric mean is the average of numbers, which is calculated by multiplying the numbers and taking the appropriate root. In statistics, the measures we use to calculate the central tendency of the whole data set are mean, median, and mode. The mean is a statistical measure that calculates the average of a dataset, providing insight into its overall distribution. In this topic, we are going to learn about geometric mean, the relation, and differences between GM, AM, HM, and its uses in our daily lives.
Geometric mean is the average of a set of data that is calculated by multiplying the ‘n’ variables and then taking the nth root. The nth root is the total number of values in the dataset. This is why the geometric mean is also defined as the nth root of the product of ‘n’ numbers.
It must be noted that geometric mean is different from arithmetic mean, where the data values are added and then divided by the total number of values. To calculate the geometric mean, we use the formula:
Geometric mean (GM) = √nx1 × x2 × x3 ......× xn
Here n is the total number of terms.
Students sometimes get confused between AM and GM so we are going to discuss the differences between Arithmetic mean and Geometric mean:
Arithmetic Mean |
Geometric Mean |
The arithmetic mean is the sum of all numbers divided by the total number count in a dataset. |
The geometric mean is the nth root of the product of the values in the dataset. Where nth root is the total number of values in a dataset. |
The formula we use is: AM = x1 + x2 + x3 ......+ xnn |
The formula we use is: GM = nx1 × x2 × x3 ......× xn |
We use arithmetic mean when we want to calculate a general average of the values, such as test scores or income |
We use geometric mean when we want to calculate population growth or investment returns. |
For example, the arithmetic mean of 2, 3, and 5 is: 2 + 3 + 53 = 103 ≈ 3.33 |
For example, the geometric mean of 2, 3, and 5 is: 32 × 3 × 5 ≈ 3.11 |
Let us first understand what AM, GM, and HM mean before learning how they are related to one another.
The arithmetic mean (AM) is the average of two or more numbers. It is calculated by adding all the numbers and then dividing the sum by the total count. The formula we use is:
x1 + x2 + x3 ......+ xnn
Geometric mean is when we multiply all the numbers of the dataset and take the nth root. Where nth is the total number of values in the dataset. The formula we use:
GM = nx1 × x2 × x3 ......× xn
Harmonic mean is a type of Pythagorean mean, where we divide the numbers of terms in the data by the sum of all reciprocal terms. The formula we use is n1x1 + 1x2 + 1x3 ..... + 1x3
Now that we have understood the meaning of each of them, let us take a look at how they are related to each other.
For two positive numbers a and b:
Arithmetic mean (AM): AM = a + b2
Geometric Mean (GM): GM = a × b
Harmonic Mean (HM): HM = 21a + 1b = 2aba + b
Now we multiply AM and HM:
AM × HM = (a + b2) × (2aba + b)
(a + b) cancels out in the numerator and denominator we get:
AM × HM = a × b × a × b = (GM)2
So the relation between AM, HM, and GM is: GM2 = AM × HM.
Now that we know the relationship between geometric mean, arithmetic mean, and harmonic mean. Let us now learn how to calculate the geometric mean using the formula. nx1 × x2 × x3 ......× xn
Here n is the total number of values, x1, x2, and so on are the numbers in the dataset.
Let us use this formula in an example,
Find the geometric mean of two numbers (2 and 8)
The formula is GM = nx1 × x2 × x3 ......× xn
GM = 2 × 8=16=4
Geometric mean is widely used in our daily lives. Here are some real-world applications of where we use geometric mean.
Students can make mistakes when solving geometric mean. So here are a few mistakes that students make and ways to avoid them:
Find the geometric mean of 2, 3, and 6
GM ≈ 3.30
Use the formula GM = nx1 × x2 × x3 ......× xn
Multiply the numbers: 2 × 3 × 6 = 36
Take the cube root (since there are 3 numbers): 336 ≈ 3.30
Find the geometric mean of 2, 3, 4, and 5
GM ≈ 3.34
nx1 × x2 × x3 ......× xn
Multiply the numbers: 2 × 3 × 4 × 5
Take the 4th root (because there are 4 numbers): 4120 ≈ 3.34
Find the geometric mean 4, 16, and 64.
GM = 16
Use the formula nx1 × x2 × x3 ......× xn
Multiply the numbers: 4 × 16 × 64
Take the cube root (for 3 numbers): 34096 = 16
Here five numbers 1, 3, 9, 27, and 81. Find the geometric mean.
GM = 9
Use the formula nx1 × x2 × x3 ......× xn
Multiply the numbers: 1 × 3 × 9 × 27 × 81 = 59049
Take the 5th root: 559049 = 310/5 = 32 = 9
There are three numbers 10, 20, and 30. Find the geometric mean.
GM ≈ 18.17
Use the formula nx1 × x2 × x3 ......× xn
Multiply the numbers: 10 × 20 × 30 = 6000.
Take the cube root (because there are a total of 3 values): GM = 36000 ≈ 18.17