There are 5 physics books and 1 chemistry book on shelf P and 3 physics books on shelf Q. One book is moved from shelf P to shelf Q. A student picks up a book from shelf Q. What is the probability that the chemistry book is taken by the student?  Pick one:
A) 1/42
B) 1/36
C) 1/30
D) 1/24
E) 1/18
P(a chemistry book is moved to shelf Q) = 1/6   P(a chemistry book is then chosen from shelf Q) = 1/4   P(the student takes a chemistry book) = 1/6 * 1/4 = 1/24   The answer is 1/24.
<result>D</result>
There are 5 physics books and 1 chemistry book on shelf P and 3 physics books on shelf Q. One book is moved from shelf P to shelf Q. A student picks up a book from shelf Q. What is the probability that the chemistry book is taken by the student?