Question

Your personal library contains books written by 165 authors. 60% of the authors are men. 40% of the authors write only nonfiction works. Also, 40 of the male authors write only nonfiction works. Assuming that your library has only one book by each author, what is the probability that a book picked at random is either a work written by an author who writes only nonfiction or a work written by a man?

Answer 1

Lets discern the infomation:

number_men = 165*0.6 = 99

so there are 99 men

non_fiction = 165 * 0.4 = 66

so 66 authors write non-fiction.

men writing non-fiction are 40, so 59 men write fiction, and 26 women write non-fiction.

probability of author non-fiction or man?
non-fiction: 40 men + 26 women = 66 total
man writers = 99

so in total 99 man + 26 women = 115 authors

hence the probability is:
115/165 = 69.6%