xpert787

lol this is not to bad, if there are 4 choices and he is randomly guessing then he has a 25% prob to answer each one correctly 1 out of 4. If he answers 2 of these by guessing then his odds are .25*.25 = .0625 or 6.25% chance of getting them both, if he answers 4 its (.25)^4 or .0039
.39% chance of getting 4 right. Its important to note if he can narrow it down to a 50/50 this helps alot.
*edit* I though about it a bit more and I think the odds are lower then .0039, because he would also have to get the other 16 questions wrong. .75^16= .010. The probability of two independent events happening is found by multiplying them so .010*.0039= .000039 or .0039%. Looks like this isn't one of your choices, I may be wrong let me know how he shows you to do it.