In this, we are using following formula directly in the code:

Geometric Mean :Average : Harmonic mean :

Example 1. Program to calculate arithmetic mean in C

Program:

#include<stdio.h>


int main ()
{
  int i, size;
  float arr[10], arithmeticMean;
  float sum = 0;
  printf ("Please enter the number of elements = ");
  scanf ("%d", &size);
  printf ("Now, enter the elements \n");
  for (i = 0; i < size; i++)
    {
      printf ("Element %d : ", i + 1);
      scanf ("%f", &arr[i]);
    }
    
  for (i = 0; i < size; i++)
    {
      sum = sum + arr[i];
    }
    
  arithmeticMean = (float) (sum / size);

  printf
    ("\n Average or Arithmetic Mean = %.2f", arithmeticMean);

  return 0;
}

Output

Please enter the number of elements = 9
Now, enter the elements 
Element 1 : 1
Element 2 : 2
Element 3 : 3
Element 4 : 4 
Element 5 : 5
Element 6 : 6
Element 7 : 7
Element 8 : 8
Element 9 : 9

 Average or Arithmetic Mean = 5.00

Example 2. Program to calculate Harmonic mean in C

Program:

#include<stdio.h>


int main (){
  int i, size;
  float arr[10], oneNthValue = 0;
  float harmonicMean;
  printf ("Please enter the number of elements = ");
  scanf ("%d", &size);
  printf ("Now, enter the elements \n");
  for (i = 0; i < size; i++) {
      printf ("Element %d : ", i + 1);
      scanf ("%f", &arr[i]);
    }

  for (i = 0; i < size; i++) {
      oneNthValue = oneNthValue + 1 / arr[i];
    }

  harmonicMean = (float) size / oneNthValue;

  printf ("\n Harmonic mean= %.2f ", harmonicMean);

  return 0;
}

Output:

Please enter the number of elements = 5
Now, enter the elements 
Element 1 : 2
Element 2 : 4
Element 3 : 6
Element 4 : 8
Element 5 : 10

 Harmonic mean= 4.38

Example 3. Program to calculate Geometric mean in C

Program: 

#include<stdio.h>
#include<math.h>


int main ()
{
  int i, size;
  double product = 1, root;
  float arr[10], oneNthValue = 0;
  float geometricMean;
  printf ("Please enter the number of elements = ");
  scanf ("%d", &size);
  printf ("Now, enter the elements \n");
  for (i = 0; i < size; i++)
    {
      printf ("Element %d : ", i + 1);
      scanf ("%f", &arr[i]);
    }
    
  for (i = 0; i < size; i++)
    {
      product = (double) product *arr[i];
    }
    
  root = (double) 1 / size;
  geometricMean = (float) pow (product, root);

  printf("Geometric mean = %.2f", geometricMean);

  return 0;
}

Output:

Please enter the number of elements = 5
Now, enter the elements 
Element 1 : 12
Element 2 : 23
Element 3 : 14
Element 4 : 11
Element 5 : 17
Geometric mean = 14.85

Write a program that reads a series of n numbers and calculates the average, geometric and harmonic mean of n elements in an array in C 

Program:

#include<stdio.h>
#include<math.h>

/*
C program to calculate arithmetic mean, harmonic mean and geometric mean

*/
int main ()
{
  int i, size;
  double product = 1, root;
  float arr[10], oneNthValue = 0;
  float harmonicMean, averageMean, geometricMean;
  float sum = 0;
  printf ("Please enter the number of elements = ");
  scanf ("%d", &size);
  printf ("Now, enter the elements \n");
  for (i = 0; i < size; i++)
    {
      printf ("Element %d : ", i + 1);
      scanf ("%f", &arr[i]);
    }
    
  for (i = 0; i < size; i++)
    {
      oneNthValue = oneNthValue + 1 / arr[i];
      sum = sum + arr[i];
      product = (double) product *arr[i];
    }
    
  root = (double) 1 / size;
  harmonicMean = (float) size / oneNthValue;
  averageMean = (float) (sum / size);
  geometricMean = (float) pow (product, root);

  printf
    ("\n Harmonic mean= %.2f \n Arithmetic mean = %.2f \n Geometric mean = %.2f",
     harmonicMean, averageMean, geometricMean);

  return 0;
}

Output:

Please enter the number of elements = 5 
Now, enter the elements 
Element 1 : 21 
Element 2 : 3 
Element 3 : 45 
Element 4 : 76 
Element 5 : 89 
Harmonic mean= 11.69 
Arithmetic mean = 46.80 
Geometric mean = 28.61

Explanation:

1. Getting input array  from a user
2. Then, applying formula on the given set of elements , that would output average, geometric and harmonic mean