Fans of print books, who have long feared that their neighborhood bookstore will be out of business due to ebooks, can take comfort in new numbers from the Pew Research Center. Among American adults 18 or older, 69% read a print book, while 28% read an ebook in 2013. Twenty-four percent has read both kinds of books.
(a) What is the probability of a random reader having read an ebook, given that he/she read a print book?