Question

a box contain 9 novels, 7 biographies, and 5 reference books. Alyssa randomly chooses a book, then she randomly chooses another book without replacing the first book

what is the probability that she chooses two biographies ? write as decimal

Answer 1

P(choosing a biography) = 7/21, since there are 21 books in total and 7 of them are biographies.
Once you selected a biography, there are only 6 left, and 20 books total, so the probability of choosing a second biography is 6/20

Hence,
P(choosing biography one time AND choosing a biography a second time) =
P(choosing biography one time) * P(choosing biography second time)
= 7/21 * 6/20 = 1/10 = 0.1