LetterGrade + QuebecLetterGrade

The QuebecLetterGrade uses the simple LetterGrade enumeration and assigns specific ranges of percentage marks for the possible LetterGrade values.

Problem Statement

Write the code for the LetterGrade class that represents a letter grade as assigned in Quebec universities (Source: http://en.wikipedia.org/wiki/Letter_grade). The solution must meet the following requirements (new requirements are in bold):

• Should get and set the grade as a type-safe value
• Should get the appropriate descriptions for the grade, based on the following table:

Grade | Description
A | A - 80-100% - Greatly Above Standards
B | B - 70-79% - Above Standards
C | C - 60-69% - At Government Standards
D | D - 50-60% - Lower Standards
F | F - 0-49% - Failure

Use the following class diagram when creating your solution.

public enum LetterGrade
{
    A, B, C, D, F
}

public class QuebecLetterGrade
{
    public LetterGrade Grade { get; set; }

    public QuebecLetterGrade(LetterGrade grade)
    {
        this.Grade = grade;
    }

    public override string ToString()
    {
        string description;
        switch (Grade)
        {
            case LetterGrade.A:
                description = "A - 80-100% - Greatly Above Standards";
                break;
            case LetterGrade.B:
                description = "B - 70-79% - Above Standards";
                break;
            case LetterGrade.C:
                description = "C - 60-69% - At Government Standards";
                break;
            case LetterGrade.D:
                description = "D - 50-60% - Lower Standards";
                break;
            case LetterGrade.F:
                description = "F - 0-49% - Failure";
                break;
            default:
                description = "Invalid Letter Grade";
                break;
        }
        return description;
    }
}