Answer:
The following assumption will be made for this assignment;
- If average score is greater than 75, the letter grade is A
- If average score is between 66 and 75, the letter grade is B
- If average score is between 56 and 65, the letter grade is C
- If average score is between 46 and 55, the letter grade is D
- If average score is between 40 and 45, the letter grade is E
- If average score is lesser than 40, the letter grade is F
The program is written in Java and it uses comments to explain difficult lines. The program is as follows
import java.util.*;
public class Tests
{
 public static void main(String [] args)
 {
  //Declare variables
  Scanner input = new Scanner(System.in);
  String firstname, lastname;
  //Prompt user for name
  System.out.print("Enter Lastname: ");
  lastname = input.next();
  System.out.print("Enter Firstname: ");
  firstname = input.next();
  char grade;
  //Declare Array
  int[] Scores = new int[5];
  //Initialize total scores to 0
  int total = 0;  
  	//Decalare Average
  	double   average;
  //Prompt user for scores
  for(int i =0;i<5;i++)
  {
  	System.out.print("Enter Score "+(i+1)+": ");
  	Scores[i] = input.nextInt();
  	//Calculate Total Scores
  	total+=Scores[i];
  }
  //Calculate Average
  average = total/5.0;
  //Get Letter Grade
  if(average>75)
  {
  grade = 'A';
  }
  else if(average>65)
  {
  grade = 'B';
  }
  else if(average>55)
  {
  grade = 'C';
  }
  else if(average>45)
  {
  grade = 'D';
  }
  else if(average>40)
  {
  grade = 'E';
  }
  else
  {
  grade = 'F';
  }
  //Print Student Results
  System.out.print("Fullname: "+lastname+", "+firstname);
  System.out.print('\n');
  System.out.print("Total Scores: "+total);
  System.out.print('\n');
  System.out.print("Average Scores: "+average);
  System.out.print('\n');
  System.out.print("Grade: "+grade);
 }
}
See Attachment for .java file