Design the following program on VB
1. Design the GUI and code for a program that will allow a user to enter three test scores. The program should then calculate the test average and display it.
2. Include clearing the values when the user starts entering a new test score in the first text box, designating a default button, and using string concatenation and formatting to display the result.
3. Include highlighting the text in the text boxes when the focus is received, testing the input for each test score to ensure that it is between 0 and 100, and disallowing any characters to be input except numbers and the period.
4. Use the FormClosing event and a message box to determine if the user truly wants to close the form.
5. Use a one-dimensional array to store the entered test scores, and then compute the average from the array.
6. Add a button that will write the test scores and the average to a sequential file.
7. Implement a class that calculates the average score of three test scores.