C programs to calculate the sum and the average of N numbers have been shown here. The result can be obtained using array and also without using array.

## 1. Algorithm to find the sum and average of N numbers

1. Take number of terms $n$ as inputs.

2. Set $s = 0$ and $i = 0$

3. Take a number $x$ as input.

4. Perform $s = s + x$ and $i = i + 1$

5. Check if $i < n$, then go to step 3, else go to step 6

6. Display $s$ as the sum and $\frac{s}{n}$ as the average and exit program.

## 2. Pseudocode to find the sum and average of N numbers

Input: Number of terms $n$

Output: Sum and average of those $n$ terms

1. Procedure sumAverage($n$):

2. $sum \leftarrow 0$

3. $i \leftarrow 0$

4. Repeat for each $i < n$:

5. Read a number $x$

6. $sum \leftarrow sum + x$

7. $i \leftarrow i + 1$

8. $avg \leftarrow \frac{sum}{n}$

9. Return $sum$, $avg$

10. End Procedure

## 3. Time complexity to find the sum and average of N numbers

Time Complexity: O(n)

Here $n$ is the number of terms.

## 4. C Program & output to calculate sum & average of n numbers without array

Code has been copied
/***********************************
alphabetacoder.com
C Program to calculate sum and
average of n numbers without array
************************************/

#include<stdio.h>

int main() {
// delclare variables
int i, n, num, sum = 0;
float avg;

// take input of number of elements
printf("Enter no of elements: ");
scanf("%d", & n);

// take input of numbers one by one
// add each number to sum
printf("Enter %d elements: \n", n);
for (i = 1; i <= n; i++) {
scanf("%d", & num);
sum = sum + num;
}

// calculate average
avg = (float) sum / n;

// display result
printf("Sum: %d\n", sum);
printf("Average: %f\n", avg);

return 0;
}


Output

Enter no of elements: 6

Enter 6 elements:

4

6

1

5

10

4

Sum: 30

Average: 5.000000

## 5. C Program to calculate sum & average of n numbers using array

Code has been copied
/*******************************
alphabetacoder.com
C Program to calculate sum and
average of n numbers using array
*********************************/

#include<stdio.h>

int main() {
// delclare variables
int i, n, N[20] = {0}, sum = 0;
float avg;

// take input of number of elements
printf("Enter no of elements: ");
scanf("%d", & n);

// take input and store into array
printf("Enter %d elements: \n", n);
for (i = 0; i < n; i++) {
scanf("%d", & N[i]);
}

// perform sum of array elements
for (i = 0; i < n; i++) {
sum = sum + N[i];
}

// calculate average
avg = (float) sum / n;

// display result
printf("Sum: %d\n", sum);
printf("Average: %f\n", avg);

return 0;
}


Output

Enter no of elements: 7

Enter 7 elements:

4

9

1

10

11

9

3

Sum: 47

Average: 6.714286