C Program to Calculate the Mean and Standard Deviation

For a list of numbers x whose elements are referred to as x₀, x₁,……, x_n-1, the mean bar x and the standard deviation a are defined as

The program given below calculates the values of bar x and sigma. It uses array x of type float to store the given numbers (maximum 50) and variable n of type int to represent the number of elements in array x. Also, the variables sum, mean and sd (all of type float) are used to represent the sum, mean and standard deviation, respectively, of the given numbers.

/* Calculate mean and standard deviation */
#include <stdio.h>
#include <math.h>
void main() {
 float x [50]; /* max. 50 elements in array x */
 int n; /*number of elements in array x */
 float sum, mean, sd; /* sum, mean and standard deviation.*/
 int i;
 clrscr();
 /* read data */
 printf("How many numbers (max 50)? ");
 scanf("%d", &n);
 printf ("Enter numbers: ");
 for(i = 0; i<n; i++)
 scanf("%f", &x[i]);
 /* calculate mean */
 sum= 0.0;
 for(i = 0; i < n; i++)
   sum+= x[i];
   mean = sum / n;
   /* calculate standard deviation */
   sum= 0.0;
 for(i = 0; i < n; i++)
   sum+= (x[i] - mean) * (x[i] - mean);
   sd = sqrt(sum / n);
   printf("Mean = %6.3f\n", mean);
   printf("Standard Deviation: %6.3f\n", sd);
   getch();
}