Lesson guide
What this Python exercise practices
Classify Exam Grade is a intermediate practice lesson that focuses on python practice, coding exercises, test feedback. It is designed to be solved in about 15 minutes with examples, starter code, and test feedback.
Prerequisites
- Python basics
- Variables
- Reading simple prompts
Difficulty and time
- Level
- Intermediate
- Estimated time
- 15 minutes
Summary
Convert a numerical exam score into a letter grade using conditional branching.
Problem statement
Write a function classify_grade(score) that takes a numeric score (int or float) and returns a letter grade according to the scale: - 90 to 100 -> 'A' - 80 to 89.999... -> 'B' - 70 to 79.999... -> 'C' - 60 to 69.999... -> 'D' - 0 to 59.999... -> 'F' If the score is outside the range 0 to 100, return the string 'Invalid score'. Use precise boundary handling so that 90.0 yields 'A', 89.999 yields 'B', etc.
Task
Implement grade classification using if/elif/else and handle invalid scores.
Examples
High score
Input
95
Output
A
Explanation
95 lies between 90 and 100 inclusive, so the grade is 'A'.
Input format
A single number (int or float) representing the score.
Output format
Return a string: one of 'A', 'B', 'C', 'D', 'F', or 'Invalid score'.
Constraints
Scores may be floats. Treat 0 <= score <= 100 as valid; everything else is invalid.
Samples
Sample input 0
89.5
Sample output 0
B
Explanation 0
89.5 is >=80 and <90, so it's a 'B'.
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