Question

A certain CS professor gives 100 -point exams that are graded on the scale \(90-100: A, 80-89: B, 70-79: C, 60-69: D,<60: F .\) Write a program that accepts an exam score as input and prints out the corresponding grade.

Short answer

Write a program with conditional statements to map scores to grades.

Step-by-step solution

Understand the Grade Distribution

First, examine the grade distribution provided by the professor. The distribution translates numerical scores into letter grades as follows: - Score between 90 and 100: Grade is A - Score between 80 and 89: Grade is B - Score between 70 and 79: Grade is C - Score between 60 and 69: Grade is D - Score less than 60: Grade is F. This grade mapping provides the basis for conditional logic in our program.

Write the Initial Program Structure

Begin by writing the program structure in a chosen programming language. Here, we assume the use of Python. Set up the program to accept an exam score as input from the user. This can be done using the `input()` function and converting the input to an integer: ```python score = int(input('Enter the exam score: ')) ```

Implement Conditional Statements

Use conditional statements to map the score to a corresponding grade. This involves checking the score against the ranges defined in the problem: ```python if score >= 90: grade = 'A' elif score >= 80: grade = 'B' elif score >= 70: grade = 'C' elif score >= 60: grade = 'D' else: grade = 'F' ```

Output the Grade

Finally, output the calculated grade using the `print()` function. This step ensures that the user is informed of their performance based on the score they entered: ```python print(f'The corresponding grade is: {grade}') ```

Key concepts

Conditional Statements

Conditional statements are a vital part of programming, allowing a program to make decisions and execute certain blocks of code based on specific conditions. In Python, this is primarily handled using `if`, `elif`, and `else`. By checking conditions, your program can provide different outputs or perform different actions.
Using `if`, we begin by setting a condition. If this condition evaluates to `True`, the code block following it will run.

• The `else` statement follows an `if`, providing an alternative path if the `if` condition is `False`.
• For multiple conditions, `elif` (short for "else if") allows the program to check additional conditions if the previous conditions are not met.

Conditional statements are linear in flow, ensuring the program checks conditions from top to bottom and stops at the first `True` condition.
For our grade calculation exercise, this structure effectively maps numeric scores to letter grades.

Grade Calculation

Grade calculation involves mapping numerical scores to predefined categories. This is essential in educational settings to provide a quick interpretation of a student's performance.
In this context, the numerical score from exams is translated to letter grades (A, B, C, D, or F) based on predefined score intervals.

• A score from 90 to 100 earns an 'A'.
• A score from 80 to 89 results in a 'B'.
• Scores from 70 to 79 get a 'C'.
• Scores between 60 and 69 are marked as 'D'.
• Any score below 60 falls under 'F'.

This mapping is not just mechanical; it reflects performance levels, helping identify areas that may need improvement or reward consistent achievement.
Using conditional statements, these intervals are directly translated into Python, allowing for efficient and clear program logic.

User Input Handling

User input handling is the process by which a program receives information from a user. In Python, this is typically done using the `input()` function, which prompts the user and captures their response as a string.
It's crucial to convert this string input to the appropriate data type for the task at hand. Since our grading program needs numerical input, we convert the string to an integer using `int()`. This conversion is key to ensuring that we can correctly compare the input against our score ranges.

• Prompt the user clearly using `input()`, which makes the program intuitive and easy to use.
• Immediately handle errors by wrapping input conversion in a try-except block, enhancing the robustness of the program.
• Feedback is key; ensure any output (like calculated grades) is clear and informative.

Handling user input efficiently ensures that your program is not only interactive but also resilient to incorrect inputs, and aligns its operation with user expectations.