The modified savings calculator program is shown in Figure 8-32 in the chapter. If neces...

The modified savings calculator program is shown in Figure 8-32 in the chapter. If necessary, create a new project named Intermediate21 Project. Enter the C++ instructions from the figure into a source file named Intermediate21.cpp. Modify the program to allow the user to enter the principal. Use a sentinel value to end the program. Save and then run the program. Test the program using the following principals, followed by your sentinel value: 1000, 3000, and 10000.