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Mean
Calculating Mean

The mean, often referred to as the average, is a way to measure the center of a dataset.

The average of a set is calculated using a two-step process:

2. Divide the total sum from step one by the number of points in your dataset.
$\bar{x} = \frac{x_1 + x_2 … + x_{n}}{n}$

The equation above is used to calculate mean. x1, x2, … xn are observations from a dataset of n observations.

#### Example

Imagine that we wanted to calculate average of a dataset with the following four observations:

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##### Step One: Calculate the total
$4 + 6 + 2 + 8 = 20$
##### Step Two: Divide by the number of observations

The total is equal to 20, and the number of observations is equal to 4.

$\frac{20}{4} = 5$

The average of this dataset is equal to 5.

### Instructions

1.

In this exercise, you will use Python to find the average age of the first four authors in Le Monde’s top 100 books.

$29, 49, 42, 43$

Add the values together, and set total equal to the answer.

2.

Divide total by the number of values in the dataset, and set mean_value to the answer.

Take a look at the result in the terminal. Keep that number in your head as you progress through the lesson.