using System;

using MathNet.Numerics.Statistics;

using System.Linq;

public class Program

{

    public static void Main()

    {

        decimal[] values = new []{ 39.99m, 29.99m, 19.99m, 49.99m };

        Tuple<double, double> meanStd = values

            .Select(x=>(double)x)

            .MeanStandardDeviation();

        double mean = meanStd.Item1;

        double std = meanStd.Item2;

        Console.WriteLine("Mean = "+ mean);

        Console.WriteLine("Std = "+ std);

    }

}