Can you please help me get the HSD? I got everything else correct. Thank you.

All the questions on this assignment pertain to this research question:

A researcher investigates which strategy improves retention during a lecture activity. Subjects were randomly assigned to one of three conditions: taking notes by hand, taking notes on the computer and active listening. Subjects then answered the same questions about the lecture they experienced. Here are the results:

Taking Notes by Hand	Taking Notes by Computer	Active Listening
6	4	6
8	6	9
5	4	8
6	5	9
5	3	11
8	4	7
4	3	8