2005 CEMC Gauss (Grade 7) Problems/Problem 6
Problem
At a class party, each student randomly selects a wrapped prize from a bag. The prizes include books and calculators. There are prizes in the bag. Meghan is the first to choose a prize. If the probability of Meghan choosing a book for her prize is , how many books are in the bag?
Solution
Since Meghan chooses a prize from in the bag and the probability of her choosing a book is , then of the prizes in the bag must be books. Therefore, the number of books in the bag is . The answer is .