C# classes referencing to get letter grade

using System;
namespace TestConsoleApplication
{
    /// <summary>
    /// Main Program
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            int[] marks = new int[5]{10,20,100,55,10};
            Grade myExam = new Grade(marks);
            Console.WriteLine("Exam = " + myExam.GetGradePercent()*100 + "%");       //Converting the decimal to Numeric value
            Console.WriteLine("Grade Letter = " + myExam.GetLetterGrade(myExam.GetGradePercent()));
            Console.ReadLine();
        }
    }
    /// <summary>
    /// Custom Class implements the Grade Functionality
    /// </summary>
    public class Grade
    {
        #region Global Variable and Constructor
        int scoresEntered;
        int[] earnedScores;
        public Grade(int[] marks)
        {
            earnedScores = marks;
        }
        #endregion
        /// <summary>
        /// Method to calculate Grade Percent
        /// </summary>
        /// <returns></returns>
        public double GetGradePercent()
        {
            double totalEarnedPoints = 0; //Start with zero
            double pointTotal = 500; //Max Marks

            //Assign variables
            scoresEntered = earnedScores.Length;
            //Add all elements of the array to total
            for (int i = 0; i < scoresEntered; i++)
            {
                totalEarnedPoints += earnedScores[i];
            }
            //Return grade percentage by dividing earned points by total points
            return totalEarnedPoints / pointTotal;
        }
        /// <summary>
        /// Method to Convert Percentage to Letter Grade
        /// </summary>
        /// <param name="percentage"></param>
        /// <returns></returns>
        public string GetLetterGrade(double percentage)
        {
            /****
             *          >97 = A+
             *  >=85 && <97 = A
             *  >=60 && <85 = B
             *  >=40 && <60 = C
             *  >=0  && <40 = D
             *******************/

            string letterGrade = String.Empty;
            percentage *= 100; 

            if (percentage >= 97.0)
            {
                letterGrade = "A+";
            }
            else if (percentage >= 85 && percentage<97)
            {
                letterGrade = "A";
            }
            else if (percentage >= 60 && percentage < 85)
            {
                letterGrade = "B";
            }
            else if (percentage >= 40 && percentage < 60)
            {
                letterGrade = "C";
            }
            else if (percentage >= 0 && percentage < 40)
            {
                letterGrade = "D";
            }
            return letterGrade;
        }
    }
}