Jeff commented that a substantial number of students found
our graded exercise 5 to be more difficult than usual.  As
a result, and because this was the last exercise before our
Test 1, Jeff has therefore provided a solutions page in pdf
form for exercise 5.  Here it is: 
  Solutions for Exercise 5.
Thanks very much to Jeff for writing up these solutions.

Jeff has also provided solutions for Exercises 10 and 11.
Here they are:
  Solutions for Exercise 10 
  Solutions for Exercise 11.
Thanks again to Jeff for writing up these solutions.