Mean and standard deviation. Write a program that reads a set of floating-point data values. Choose an appropriate mechanism for prompting for the end of the data set.

When all values have been read, print out the count of the values, the average, and the standard deviation. The average of a data set {x,...,xn) is x = x/n, where Ex= x ++x, is the sum of the input values. The standard deviation is S= (x; x) n-1