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Mean

  • Last Updated : 11 Dec, 2018

Mean is average of a given set of data. Let us consider below example 2, 4, 4, 4, 5, 5, 7, 9 the mean (average) of a given set of data is 5

Fact about Mean :

  1. The mean (or average) is the most popular and well known measure of central tendency.
  2. It can be used with both discrete and continuous data, although its use is most often with continuous data.
  3. There are other types of means.Geometric mean, Harmonic mean and Arithmetic mean.
  4. Mean is the only measure of central tendency where the sum of the deviations of each value from the mean is always zero.

Formula of mean of ungrouped data :

Formula of mean of grouped data :

How to find Mean ?
Given n size unsorted array, find its mean.



Mean of an array = (sum of all elements) / (number of elements)

Since the array is not sorted here, we sort the array first, then apply above formula.

Examples:

Input  : {1, 3, 4, 2, 6, 5, 8, 7}
Output : Mean = 4.5

Sum of the elements is 1 + 3 + 4 + 2 + 6 + 
5 + 8 + 7 = 36
Mean = 36/8 = 4.5

Input  : {4, 4, 4, 4, 4}
Output : Mean = 4

Below is the code implementation:

C++




// CPP program to find mean
#include <bits/stdc++.h>
using namespace std;
  
// Function for calculating mean
double findMean(int a[], int n)
{
    int sum = 0;
    for (int i = 0; i < n; i++)
        sum += a[i];
  
    return (double)sum / (double)n;
}
  
// Driver program
int main()
{
    int a[] = { 1, 3, 4, 2, 7, 5, 8, 6 };
    int n = sizeof(a) / sizeof(a[0]);
    cout << "Mean = " << findMean(a, n) << endl;
    return 0;
}

Java




// Java program to find mean
import java.util.*;
  
class GFG {
  
    // Function for calculating mean
    public static double findMean(int a[], int n)
    {
        int sum = 0;
        for (int i = 0; i < n; i++)
            sum += a[i];
  
        return (double)sum / (double)n;
    }
  
    // Driver program
    public static void main(String args[])
    {
        int a[] = { 1, 3, 4, 2, 7, 5, 8, 6 };
        int n = a.length;
        System.out.println("Mean = " + findMean(a, n));
    }
}

Python3




# Python3 program to find mean 
  
# Function for calculating mean
def findMean(a, n):
  
    sum = 0
    for i in range( 0, n):
        sum += a[i]
      
    return float(sum / n)
  
# Driver program
a = [ 1, 3, 4, 2, 7, 5, 8, 6 ]
n = len(a)
print("Mean =", findMean(a, n))

C#




// C# program to find mean
using System;
  
class GFG {
    // Function for
    // calculating mean
    public static double findMean(int[] a, int n)
    {
        int sum = 0;
        for (int i = 0; i < n; i++)
            sum += a[i];
  
        return (double)sum / (double)n;
    }
  
    // Driver Code
    public static void Main()
    {
        int[] a = { 1, 3, 4, 2,
                    7, 5, 8, 6 };
        int n = a.Length;
        Console.Write("Mean = " + findMean(a, n) + "\n");
    }
}

PHP




<?php 
// PHP program to find mean 
  
// Function for calculating mean
function findMean(&$a, $n)
{
    $sum = 0;
    for ($i = 0; $i < $n; $i++) 
        $sum += $a[$i];
      
    return (double)$sum
           (double)$n;
}
  
// Driver Code
$a = array(1, 3, 4, 2, 
           7, 5, 8, 6);
$n = sizeof($a);
echo "Mean = "
      findMean($a, $n)."\n"
?>


Output:
Mean = 4.5

Time Complexity to find mean = O(n)

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