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Average Monthly Electricity Bill

Concept Explanation

What is it?

This program calculates the average (mean) of three given electricity bills. The average is a measure of central tendency, representing a typical value for a set of numbers. It's found by summing all values and dividing by the count of those values.

Why is it important?

Calculating averages is a very common task in data analysis, statistics, and everyday life. In programming, it serves as a straightforward example of applying arithmetic operations to a small dataset to derive a meaningful summary.

Where is it used?

• Personal Finance: Tracking average monthly expenses or income.
• Business Analytics: Calculating average sales, customer spending, or production costs.
• Science and Research: Determining average experimental readings or environmental data.
• Performance Metrics: Averaging performance scores, response times, etc.

Real-world example

If your electricity bills for the last three months were $23, $32, and $64, calculating the average helps you understand your typical monthly expenditure. The sum is $23 + $32 + $64 = $119. The average is $119 / 3 = $39.67. This average gives you a single figure to budget around.

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Algorithm

1. Start.
2. Define or get three electricity bills (bill1, bill2, bill3).
3. Calculate the total sum of the bills: total_bill = bill1 + bill2 + bill3.
4. Calculate the average monthly bill: average_bill = total_bill / 3.
5. Display the individual bills, total bill, and the calculated average monthly bill.
6. End.

Edge Cases:

• Non-numeric input for bills (handled by language-specific error mechanisms or explicit validation).
• Zero or negative bill amounts (program will handle them mathematically, but negative bills are not realistic in this context and might require validation).

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Implementations

Java (JDK 17)

public class AverageElectricityBill {
    public static void main(String[] args) {
        // Electricity bills for the last three months (can be user input in a modified version)
        double bill1 = 23.0;
        double bill2 = 32.0;
        double bill3 = 64.0;

        // Calculate the sum of the bills
        double totalBill = bill1 + bill2 + bill3;

        // Calculate the average monthly bill
        double averageBill = totalBill / 3;

        System.out.println("Electricity Bill - Month 1: $" + bill1);
        System.out.println("Electricity Bill - Month 2: $" + bill2);
        System.out.println("Electricity Bill - Month 3: $" + bill3);
        System.out.println("Total Bill for three months: $" + String.format("%.2f", totalBill)); // Formatted for clarity
        System.out.println("Average Monthly Electricity Bill: $" + String.format("%.2f", averageBill));
    }
}

Python (3.10+)

# Electricity bills for the last three months
bill1 = 23.0
bill2 = 32.0
bill3 = 64.0

# Calculate the sum of the bills
total_bill = bill1 + bill2 + bill3

# Calculate the average monthly bill
average_bill = total_bill / 3

print(f"Electricity Bill - Month 1: ${bill1}")
print(f"Electricity Bill - Month 2: ${bill2}")
print(f"Electricity Bill - Month 3: ${bill3}")
print(f"Total Bill for three months: ${total_bill:.2f}")
print(f"Average Monthly Electricity Bill: ${average_bill:.2f}")

C (C99)

#include <stdio.h>

int main() {
    double bill1 = 23.0; // Electricity bill for month 1
    double bill2 = 32.0; // Electricity bill for month 2
    double bill3 = 64.0; // Electricity bill for month 3
    double average_bill;

    // Calculate the average monthly electricity bill
    average_bill = (bill1 + bill2 + bill3) / 3.0;

    printf("Electricity Bill - Month 1: $%.2lf", bill1);
    printf("Electricity Bill - Month 2: $%.2lf", bill2);
    printf("Electricity Bill - Month 3: $%.2lf", bill3);
    printf("Total Bill for three months: $%.2lf", bill1 + bill2 + bill3); // Display total as well
    printf("Average Monthly Electricity Bill: $%.2lf", average_bill);

    return 0;
}

Oracle (19c)

SET SERVEROUTPUT ON;
DECLARE
  bill1       NUMBER := 23;
  bill2       NUMBER := 32;
  bill3       NUMBER := 64;
  total_bill  NUMBER;
  average_bill NUMBER;
BEGIN
  DBMS_OUTPUT.PUT_LINE('--- Average Monthly Electricity Bill ---');
  DBMS_OUTPUT.PUT_LINE('Electricity Bill - Month 1: $' || bill1);
  DBMS_OUTPUT.PUT_LINE('Electricity Bill - Month 2: $' || bill2);
  DBMS_OUTPUT.PUT_LINE('Electricity Bill - Month 3: $' || bill3);

  total_bill := bill1 + bill2 + bill3;
  average_bill := total_bill / 3;

  DBMS_OUTPUT.PUT_LINE('Total Bill for three months: $' || ROUND(total_bill, 2));
  DBMS_OUTPUT.PUT_LINE('Average Monthly Electricity Bill: $' || ROUND(average_bill, 2));
END;
/

Explanation

• Java: Uses double to handle monetary values. The bills are hardcoded but can be easily modified to take user input. String.format("%.2f", ...) ensures currency formatting.
• Python: Bills are hardcoded as floats. Uses standard arithmetic operators. f-strings format the output to two decimal places.
• C: Uses double for bill amounts. Hardcoded values are used. printf("$%.2lf", ...) formats the output for currency.
• Oracle: Implemented in PL/SQL. Uses NUMBER data type. Bills are hardcoded constants. ROUND() is used for formatting the output to two decimal places.

Complexity Analysis

• Time Complexity: O(1) - The number of arithmetic operations is constant.
• Space Complexity: O(1) - A fixed number of variables are used.

Flowchart

Sample Dry Run

Step	bill1	bill2	bill3	Total Bill	Average Bill	Description
Initial	23.0	32.0	64.0	-	-	Bills are defined
Process	23.0	32.0	64.0	119.0	-	Total Bill = 23.0 + 32.0 + 64.0 = 119.0
Process	23.0	32.0	64.0	119.0	39.67	Average Bill = 119.0 / 3 = 39.666... (rounded to 39.67)
Output	-	-	-	-	-	Display bills, total, and average
End	-	-	-	-	-	Program terminates

Practice Problems

Easy

• Modify the program to take the three bills as user input.
• Calculate the average of N bills, where N is also provided by the user.

Medium

• Implement a system to track bills over a year and calculate monthly, quarterly, and annual averages.
• Add input validation to ensure bill amounts are positive.

Hard

• Create a budgeting tool that uses historical average bill data to predict future expenses and alert users if their current spending is above average.

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"The only source of knowledge is experience." - Albert Einstein