Write a C++ program that includes two functions named calcavg() and variance(). The calcavg() function should calculate and return the average of values stored in an array named testvals. The array should be declared in main() and include the values 89, 95, 72, 83, 99, 54, 86, 75, 92, 73, 79 75, 82, and 73. The value returned calavg() should be displayed by using cout statement in main().