Create Average_Mean.md (TheAlgorithms#35)

PatOnTheBack · AnupKumarPanwar · commit e384338840c1 · 2019-07-04T13:17:31.000+05:30
Explain how to calculate an average (mean) of a list of numbers.
diff --git a/Basic Math/Average_Mean.md b/Basic Math/Average_Mean.md
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+# Average (Mean)
+
+Calculate the average of a list of numbers using mean.
+
+## Applications
+
+Calculating the mean of a list of numbers is one of the most common ways to
+determine the average of those numbers.
+
+Calculating a mean would be useful in these situations:
+
+-   Determining the average score for all players of a video game level.
+-   Finding the average grade for tests that a student took this semester.
+-   Determining the average size of all files in a directory/folder.
+
+## Steps
+
+1.  Input a list of numbers.
+2.  Calculate the sum of all numbers in the list.
+3.  Count the numbers in the list.
+4.  Divide the sum by the total count of numbers in the list.
+5.  Return mean.
+
+## Example
+
+Given the list `[2, 4, 6, 8, 20, 50, 70]`, let's calculate the average.
+
+### Step 1
+
+Send `[2, 4, 6, 8, 20, 50, 70]` as input for a method/function.
+
+### Step 2
+
+Add all the numbers together.
+
+`2 + 4 + 6 + 8 + 20 + 50 + 70 = 160`, so `sum = 160`.
+
+### Step 3
+
+Count the numbers in the list.
+
+The list has seven numbers, so `count = 7`.
+
+### Step 4
+
+Divide the sum of all the numbers by the count of the numbers.
+
+```
+sum = 160
+count = 7
+```
+If we ignore significant digits: `sum / count = `22.<u>857142</u>
+
+If we properly consider significant digits: `sum / count = 23`
+
+### Step 5
+
+Return the value of 22.<u>857142</u> or `23`.
+
+## Implementation
+
+-   [Python](https://github.com/TheAlgorithms/Python/blob/master/maths/average.py)
+
+## Video URL
+
+-   [Mean on Khan Academy](https://www.khanacademy.org/math/ap-statistics/summarizing-quantitative-data-ap/measuring-center-quantitative/v/mean-median-and-mode)
+
+## Others
+
+-   [Mean on Wikipedia](https://en.wikipedia.org/wiki/Mean)
