Actually this isn't homework for a class.
I know this is two years after the fact. Just the same, I thought someone should set the record straight – if for no other reason, then because jeffa has linked to the OP has an example of homework in his oft cited How (Not) To Ask A Question tutorial.
So I did a quick search. I just googled for the fourth question. Imagine my surprise when I found that Google returned exactly two links.
The first was a link to the archived OP at thepen, blakem's Perl Monks archive.
The second was http://home.earthlink.net/~greenblanket/cs551-gradedperl.htm.
You be the judge. ;-)
"My two cents aren't worth a dime.";