Question

a bookcase contains 2 statistics books and 5 biology books if 2 books are chosen at random the chance that both are statistics books is

Answer 1

Answer 1 (without replacement) :

P(2 books)=P(first)*P(second)=2/7*1/6=2/42=1/21 this is if you don't put the book back on the shelf after taking it off the first time

Answer 2 (with replacement) :

P(2 books)=P(first)*P(second)=2/7*2/7=4/49 this is if you put the book back on the shelf after taking it off the first time

I put he probably didn't put the book back on the shelf after this first time but I don't know without those details in the question

Answer 2

it would be a 1/21 chance to get a statistics book if you don't replace the books but it would be a 4/49 chance to get a statistics book with replacing the books