3) Use a Sentinel loop. Prompt the user to enter their test scores ( 0 to 100 ). Negative number to quit. Calculate average test score. Use multiple if() commands to print out a message with their class grade (A, B, C, D, F). Output the letter grade. Using the given class grading scale below. A = 90 to 100 points B = 80 to 89 points C = 70 to 79 points F = 69 points or below 4) Repeat problem 3 above, but use a switch statement instead of multiple if() commands - i.e. replace multiple if() statements with a switch statement