diff --git a/gradebook/src/GradeBook/Book.cs b/gradebook/src/GradeBook/Book.cs
index d75d2c2..3c8262a 100644
--- a/gradebook/src/GradeBook/Book.cs
+++ b/gradebook/src/GradeBook/Book.cs
@@ -26,12 +26,21 @@ namespace GradeBook
             result.highGrade = double.MinValue;
             result.lowGrade = double.MaxValue;
 
-            foreach (var grade in this.grades)
+            // foreach (var grade in this.grades)
+            // {
+            //     result.lowGrade = Math.Min(grade, result.lowGrade);
+            //     result.highGrade = Math.Max(grade, result.highGrade);
+            //     result.Average += grade;
+            // }
+
+            var index = 0;
+            do
             {
-                result.lowGrade = Math.Min(grade, result.lowGrade);
-                result.highGrade = Math.Max(grade, result.highGrade);
-                result.Average += grade;
-            }
+                result.lowGrade = Math.Min(grades[index], result.lowGrade);
+                result.highGrade = Math.Max(grades[index], result.highGrade);
+                result.Average += grades[index];
+                index += 1;
+            } while (index < grades.Count);
 
             result.Average /= grades.Count;
             return result;