Mean and standard deviation.
Write a program that reads a set of floating-point data values from the input. When the user indicates the end of input, print out the count of the values, the average, and the standard deviation. The average of a data setx1, . . . , xn is
a = (Σxi)/n
where Σxi = x1 + . . . + xn is the sum of the input values. The standard deviation is
s = √(Σ(xi - a)2 / (n - 1)) However, that formula is not suitable for our task. By the time you have computed the mean, the individual xi are long gone. Until you know how to save these values, use the numerically less stable formula s = √(((Σxi2) - (Σxi) / n)/(n - 1)) You can compute this quantity by keeping track of the count, the sum, and the sum of squares in the DataSet class as you process the input values.