Initial data commit

Task/Averages-Root-mean-square/C-sharp/averages-root-mean-square-1.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace rms
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            int[] x = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+            Console.WriteLine(rootMeanSquare(x));
+        }
+
+        private static double rootMeanSquare(int[] x)
+        {
+            double sum = 0;
+            for (int i = 0; i < x.Length; i++)
+            {
+                sum += (x[i]*x[i]);
+            }
+            return Math.Sqrt(sum / x.Length);
+        }
+    }
+}

Task/Averages-Root-mean-square/C-sharp/averages-root-mean-square-2.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace rms
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            Console.WriteLine(rootMeanSquare(Enumerable.Range(1, 10)));
+        }
+
+        private static double rootMeanSquare(IEnumerable<int> x)
+        {
+            return Math.Sqrt(x.Average(i => (double)i * i));
+        }
+    }
+}