Let's consider the following set of books from which a winner can get 2 books:
Books = {Physics1, Physics2, Physics3, Math1, Math2, History, philosophy}
Let's write:
A is the event associated to "win a Physics book", and
B is the event associated to "win a Math book"
The probability to win, at first, a Physics book, is:
P(A) = 3/7
The probability to win a Physics book and then a Math book is:
P(A ∩ B ) = 3/7 x 2/6 = 1/7
What is the probability to win a Math book given
that it have been, at first, won a Physics book ?
