I just spoke to Prof. Buckley, and she told me that the "fraudulent" values that appear in the solutions (e.g. $z=0$, probability = .5) are due to the fact that the boxes haven't been filled in. So if you leave $\mu$'s box blank, it takes a default of 0 (or something else that you don't want), and then gives you answers appropriate for that blank information.
If you want to use IMath's problems as a study guide, then you should treat them as problems that you're doing again for homework. Fill in all the boxes, then hit "submit". Then you should be able to see your answers and the correct answers.
Let me know if other problems arise, and thanks again Nina for asking!
Prof. Long