Exam 70-761 topic 1 question 200 discussion

I guess that's exactly what is asked for: don't include double entries in the average calculation and this clearly makes a difference. If you like to try it out: -- create table CREATE TABLE dbo.Evaluations ( EvaluationID INT NOT NULL, EmployeeID INT NULL, CourseID INT NULL, Eval INT NOT NULL ); -- insert demo data INSERT INTO dbo.Evaluations (EvaluationID, EmployeeID, CourseID, Eval) VALUES (1, 5, 1, 13), (2, 10, 2, 77), (3, 10, 2, 77), -- dupe from preceding line (4, 12, 2, 28), (5, 13, 1, 51); -- results SELECT CourseID, AVG(DISTINCT Eval) AS AvgWithDistinct, AVG(Eval) AS AvgWithoutDistinct FROM Evaluations GROUP BY CourseID; -- clean up DROP TABLE dbo.Evaluations; Output: CourseID AvgWithDistinct AvgWithoutDistinct 1 32 32 2 52 60 So "AVG(DISTINCT Eval)" is the right answer from my point of view.