use today's values, they aren't going to be close in terms of the options, they'll be quite different so it'll be quite obvious what the answer is- unless jon specifically told u to look at 4 weeks ago prices.
@ sam- noone can tell u since u never get final exams back to keep. my overall mark was pretty close to how i faired in the final- found the exam to be very straightforward if you knew the stuff. wasn't the type to try and trick you and throw in stuff not focussed on in the tuts and lecs.