I have fixed some small typoes, grammar errors etc. in the problems.
Other than that, the quiz looked good to me, except for problem 4.

In Problem 4, I think the last italicized question is not quite clear.
Maybe a hint should be added that it is talking about conditional
probability.  Otherwise I think people might get confused as to what
this sentence actually means.  I think it is less than obvious that it
is not stating that probability of TA's answer being right is
independent of the probability of Lecturer's answer being right.

Adrian.