Here is Quiz 10 for corrections. Since you are already doing #3 as for your IDEAl solution, I’ll evaluate that submission in lieu of re-writing it on any corrections you turn in.
Speaking of #3, Example 20.6 outlines how to solve the problem. The Evaluate step in the text is very compressed, and I want you to give a more detailed explanation of what is going on, in your own words and maybe pictures, than Wolfson offers. What I’m most interested in is your understanding. Also note that some elements of this problem are the same as in this week’s Math Lab (particularly the way one handles the element of charge dq). The main difference is that in Math Lab you found solutions for arbitrary locations in the plane of the ring, while this problem asks for E at a specific location on the axis of the ring, but in a different plane 15 cm away. You might think about what change you’d need to make to your Mathematica notebook to solve the fully 3-dimensional problem – you may be surprised at how small the change would be!