The file Final.txt contains student grades on a final exam. Write a program using LINQ that displays the average grade on the exam and the percentage of grades that are above average. The figure below shows a possible outcome of the program:

The figure below shows the contents of Final.txt which was used to obtain the above results.  You can create this file yourself using Notepad.

 

Suggested Control Names and Attributes:

Name Property	Text Property	ReadOnly Property	Control Type	Notes
frmAverageGrade	Grades	N/A	Form	Holds Controls
btnEvaluate	Evaluate Grades	N/A	Button	Triggers event to display grade analysis
txtAverageGrade		Set to true	TextBox	Displays average grade.
txtAboveAverage		Set to true	TextBox	Displays % of grades above average.

Write the Code:

' Project: Average Grade
' Description:  This program reads a list of grades from a text file.  It uses LINQ to calculate
' and display the average grade and the percentage of grades that are above average.

Public Class frmAverageGrade
    ' Declare global variables
    Dim tempGrades() As String = IO.File.ReadAllLines("Final.txt")
    Dim grades(tempGrades.Count - 1) As Double

    Private Sub btnEvaluate_Click(sender As Object, e As EventArgs) Handles btnEvaluate.Click
        ' Load grades from temporary string array into integer array
        Dim counter As Integer = 0
        For Each grade As Integer In tempGrades
            grades(counter) = grade
            counter += 1
        Next

        ' Place values into a query for easy manipulaton
        Dim gradeQuery = From grade In grades
                         Select grade

        ' Calulate the average of the query and display it
        txtAverageGrade.Text = (gradeQuery.Average / 100).ToString("P")

        ' Determine how many grades are above average and calculate the percentage
        Dim gradeQuery2 = From grade In grades
                          Where grade > gradeQuery.Average
                          Select grade
        txtAboveAverage.Text = (gradeQuery2.Count / grades.Count).ToString("P")
    End Sub
End Class