Probability that a particular subject comes in my exam

Born2Perform

Hello,
I have an exam at july, in the oral part of it there are 5 subjects, that are choosen from a list of 7 subjects (Physics, History, Phylosophy, Art, Italian Lit., English Lit., Geology.)

Those 5 subjects are randomly picked up from a box (in wich there are the 7 subjects), with 2 conditions:

- English Literature is not in the box, and always comes.
- Or comes History, or comes Phylosophy, they can't come both, but they'r both in the box. If one is extracted, and also the other is picked up, the second picked up doesn't count.

I need to know the probabilities for each in order to know which i should study less.
i know english probability to come is 1, but this thing of "or history or philo" stopped me, i can't solve it just thinking with dices and make tables,
any suggestion?

cristo

Why not study them all, apart from one of History or Philosophy (since if one of those is on the test, then the other will not be). That way you'll be able to answer all possible questions!