A bookstore buys 15 copies of a book at a price of $20 each and sells them at a price of $30. Suppose that, after a year, the bookstore may return any unsold copies of the book to the publisher at the original price of $20. Let X be the number of copies sold during the year and assume that the probability function of X is given by

(i) Check that f (x) is a proper probability function.
(ii) Find the expected number of copies sold in a year.
(iii) Find the expected profit of the bookstore from the sales of this particular book.

Transcribed Image Text:

x+2 f(x) = x=1, 2,..., 15. 150