Find the Average of Array Elements

Problem Statement

Given an array of numbers, the task is to find the average (mean) of all elements in the array.

The average of an array is calculated using the formula:

Why This Problem Is Important

This problem introduces and reinforces:

• Array traversal
• Accumulating values using loops
• Division and type handling
• Difference between integer and floating-point results

It is widely used in:

• Statistical calculations
• Data analysis
• Performance metrics
• Real-world scoring and grading systems

Input and Output Format

Input

Array: [10, 20, 30, 40, 50]

Output

Average = 30

Key Points to Remember

• Always calculate the sum first
• Divide by the total number of elements
• Be careful with integer division in some languages
• Use floating-point data types when needed

Approach / Logic

1. Initialize sum = 0
2. Traverse the array and add each element to sum
3. Count the number of elements (n)
4. Compute average = sum / n
5. Print the average

Step-by-Step Algorithm

1. Start
2. Read the array and its size
3. Initialize sum = 0
4. Loop through the array
5. Add each element to sum
6. Divide sum by n
7. Print the average
8. End

Pseudocode

sum = 0
n = length of array

for i = 0 to n-1:
    sum = sum + arr[i]

average = sum / n
print average

Dry Run Example

Array = [4, 6, 8, 10]

sum = 0
sum = 0 + 4  → 4
sum = 4 + 6  → 10
sum = 10 + 8 → 18
sum = 18 + 10 → 28

n = 4
average = 28 / 4 = 7

Time and Space Complexity

Only one traversal is required, and no extra space is used.

Language-wise Implementation

C Implementation

#include 

int main() {
    int arr[] = {10, 20, 30, 40, 50};
    int n = sizeof(arr) / sizeof(arr[0]);
    int sum = 0;

    for(int i = 0; i < n; i++) {
        sum += arr[i];
    }

    float average = (float)sum / n;
    printf("Average of array elements: %.2f", average);

    return 0;
}

Output

Average of array elements: 30.00

C++ Implementation

#include 
using namespace std;

int main() {
    int arr[] = {10, 20, 30, 40, 50};
    int n = sizeof(arr) / sizeof(arr[0]);
    int sum = 0;

    for(int i = 0; i < n; i++) {
        sum += arr[i];
    }

    double average = (double)sum / n;
    cout << "Average of array elements: " << average;

    return 0;
}

Output

Average of array elements: 30

Java Implementation

public class Main {
    public static void main(String[] args) {
        int[] arr = {10, 20, 30, 40, 50};
        int sum = 0;

        for(int num : arr) {
            sum += num;
        }

        double average = (double) sum / arr.length;
        System.out.println("Average of array elements: " + average);
    }
}

Output

Average of array elements: 30.0

Python Implementation

arr = [10, 20, 30, 40, 50]
sum_elements = 0

for num in arr:
    sum_elements += num

average = sum_elements / len(arr)
print("Average of array elements:", average)

Output

Average of array elements: 30.0

C# Implementation

using System;

class Program {
    static void Main() {
        int[] arr = {10, 20, 30, 40, 50};
        int sum = 0;

        foreach(int num in arr) {
            sum += num;
        }

        double average = (double) sum / arr.Length;
        Console.WriteLine("Average of array elements: " + average);
    }
}

Output

Average of array elements: 30

JavaScript Implementation

let arr = [10, 20, 30, 40, 50];
let sum = 0;

for (let i = 0; i < arr.length; i++) {
    sum += arr[i];
}

let average = sum / arr.length;
console.log("Average of array elements:", average);

Output

Average of array elements: 30

Common Mistakes to Avoid

• Using integer division unintentionally
• Forgetting to type-cast before division
• Dividing before summing all elements
• Not handling empty arrays (in advanced cases)

Interview Variations

• Average of even elements only
• Average of elements at even indices
• Running average of array
• Average in a given range

Detailed Summary

Finding the average of array elements is a foundational problem that combines array traversal, accumulation, and arithmetic operations. By summing all values and dividing by the total number of elements, we compute a meaningful statistical measure. This problem emphasizes careful handling of data types, especially in languages where integer division can lead to incorrect results. Mastery of this concept is essential for progressing to more complex problems involving statistics, prefix sums, and real-time data analysis.

Next Problem in the Series

Print Array Elements in Reverse Order