Encapsulate all methods within Book class

gradebook/src/GradeBook/Book.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 
 namespace GradeBook
@@ -17,6 +18,26 @@ namespace GradeBook
         {
             this.grades.Add(grade);
         }
+
+        public void ShowStaticstics()
+        {
+            
+            double result = 0;
+            var highGrade = double.MinValue;
+            var lowGrade = double.MaxValue;
+
+            foreach (var number in this.grades)
+            {
+                highGrade = Math.Max(number, highGrade);
+                lowGrade = Math.Min(number, lowGrade);
+                result += number;
+            }
+            result /= grades.Count;
+
+            Console.WriteLine($"The average grade is {result:N1}");
+            Console.WriteLine($"The highest grade is {highGrade:N1}");
+            Console.WriteLine($"The lowest grade is {lowGrade:N1}");
+        }
     }
     
 }

gradebook/src/GradeBook/Program.cs

@@ -11,25 +11,8 @@ namespace GradeBook
             var book = new Book("Scott's Grade Book");
             book.AddGrade(89.1);
             book.AddGrade(90.5);
-
+            book.AddGrade(87.2);
-            List<double> grades = new List<double>() {12.7, 10.3, 6.11, 4.1};
+            book.ShowStaticstics();
-            grades.Add(56.1);
-            double result = 0;
-            var highGrade = double.MinValue;
-            var lowGrade = double.MaxValue;
-
-            foreach (var number in grades)
-            {
-                highGrade = Math.Max(number, highGrade);
-                lowGrade = Math.Min(number, lowGrade);
-                
-                result += number;
-            }
-            result /= grades.Count;
-
-            Console.WriteLine($"The average grade is {result:N1}");
-            Console.WriteLine($"The highest grade is {highGrade:N1}");
-            Console.WriteLine($"The lowest grade is {lowGrade:N1}");
         }
     }
 }