private static void WriteResults(IGradeTracker book)
{
GradeStatistics stats = book.ComputeStatistic();
book.AddGrade(6.5f);
foreach (var grade in book)
{
Console.WriteLine(grade);
}
WriteResult("Highest grade", (int)stats.MaxGrade);
WriteResult("Average grade", stats.AvgGrade);
WriteResult("Lowest grade", stats.MinGrade);
WriteResult("Your letter Grade is ", stats.LetterGrade);
WriteResult("And it is ", stats.LetterGradeDescription);
}