In this exercise, you create a program that calculates the average of three test scores. The program should contain two value-returning functions (main and calc Average) and two void functions (get Test Scores and display Average). The main function should call the void get Test Scores function to get three test scores. The test scores may contain a decimal place. The main function then should call the value-returning calc  Average function to calculate and return the average of the three test scores. When the calc Average function has completed its task, the main function should call the void display Average function to display the average of the three test scores on the screen. Display the average with one decimal place. Use a sentinel value to end the program.

a. Create IPO charts for the problem, and then desk-check the algorithm using the following four sets of test scores, followed by your sentinel value: 56, 78, 90; 100, 85, 67; 74, 32, 98; and 25, 99, 84.

b. List the input, processing, and output items, as well as the algorithm, in a chart similar to the one shown earlier in Figure 10-35. Then, code the algorithm into a program.

c. Desk-check the program using the same data used to desk-check the algorithm.

d. If necessary, create a new project named Advanced21 Project. Enter your C++ instructions into a source fi le named Advanced21.cpp. Also enter appropriate comments and any additional instructions required by the compiler.

e. Save and then run the program. Test the program using the same data used to desk-check the program.