A girl has exactly 5 quarters, 9 dimes, and 10 nickels in her pocket. If she withdraws a number of these coins at random, how many coins would she have to withdraw to ensure that she has at least a 50 percent chance of withdrawing at least one quarter?	Choose one: A) 2 B) 3 C) 4 D) 5 E) 6
When the probability of NOT drawing a quarter is 50% or less, then the probability of drawing a quarter is at least 50%.   P(not drawing a quarter with 2 coins) = 19/24 * 18/23 = 57/92 &gt; 50%   P(not drawing a quarter with 3 coins) = 57/92 * 17/22 = 969/2024 &lt; 50%   The answer is 3.
<result>B</result>
A girl has exactly 5 quarters, 9 dimes, and 10 nickels in her pocket. If she withdraws a number of these coins at random, how many coins would she have to withdraw to ensure that she has at least a 50 percent chance of withdrawing at least one quarter?