Chapter 3, Problem 6PP

Write a function that computes the average and standard deviation of four scores. The standard deviation is defined to be the square root of the average of the four values: ${\left(si-a\right)}^2,$ where a is the average of the four scores $s_1,s_2,s_3,$ ands $s_4.$ The function will have six parameters and will call two other functions. Embed the function in a program that allows you to test the function again and again until you tell the program you are finished.