Question

Calculate salary: Using methods.

Separating calculations into methods simplifies modifying and expanding programs.

The following program calculates the tax rate and tax to pay, using methods. One method returns a tax rate based on an annual salary.

1. Run the program below with annual salaries of 40000, 60000, and 0.
2. Change the program to use a method to input the annual salary.
3. Run the program again with the same annual salaries as above. Are results the same?

Answer 1

A program can calculate the average tax rate and taxes paid based on an annual salary. It's important to use separate methods for different calculations like tax rate determination or tax amount calculation. Ensuring program consistency after changes is achieved by running it with various salary inputs.

Step-by-step explanation:

Calculating taxes on an annual salary involves understanding the concepts of average tax rate and marginal tax rate. The average tax rate is the fraction of an individual's income paid in taxes, while the marginal tax rate refers to the tax rate on the last dollar of income. A program can be developed to calculate these rates and the resulting taxes paid using a methodological approach which simplifies modification and expansion.

For example, if someone earns a $20,000 annual salary and pays $2,581.25 in taxes, their average tax rate would be: 2,581.25 divided by 20,000, resulting in 0.129 or 12.9 percent. To calculate the entire tax owed based on a given salary, we would look at the tax brackets defined in a tax schedule. For instance, the tax might be calculated as a base amount plus a certain percentage over a threshold, such as: $837.50 + 0.15 × (20,000 - 8,375).

When expanding a program to calculate taxes, it's useful to encapsulate the logic into cohesive methods. For instance, one method could determine the tax rate based on salary, another to calculate the taxes owed, and a new method to input the annual salary. Each method isolates specific tasks, making them reusable and easier to manage. Running the program with various salaries, such as $40,000, $60,000, and $0, each time checking if the output remains consistent after changes, ensures program integrity.

Ultimately, for someone like Peter, who needs to budget for expenses like housing, understanding the difference between gross salary, net annual income (after taxes), and the monthly income is crucial when deciding the best financial option. Net annual income is what remains after calculating and deducting taxes based on the methods described above.