A girl has exactly 5 quarters, 8 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) = 18/23 * 17/22 = 153/253 &gt; 50%   P(not drawing a quarter with 3 coins) = 153/253 * 16/21 = 816/1771 &lt; 50%   The answer is 3.
<result>B</result>
A girl has exactly 5 quarters, 8 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?