<p>Out of a workbook. The problem was pretty self-explanatory after the little lesson, but I've never seen this in any official materials. here goes:
4. A bag contains 8 white marbles, 8 blue marbles, 7 red marbles, and 6 yellow marbles. What is the least number of marbles that can be drawn from the bag, so that 3 of the same color marbles will be drawn?</p>
<p>(A) 6
(B) 9
(C) 12
(D) 13
(E) 15</p>
<p>The right answer is (B).</p>
<p>Can someone explain why the answer isn’t 3?</p>
<p>^I guess you have to consider the worst-case scenario.</p>
<p>Because 3 wasn’t an answer choice? :D</p>
<p>This question is not written clearly. A question will never be written so poorly on the actual SAT.</p>
<p>
The question is asking for “will be drawn,” not “can be drawn”. </p>
<p>To account for all of the possible combinations of picking up marbles so that picking up 3 identical color marbles is guaranteed, the worst case scenario must be considered. Worst case scenario: You pick a different color marble every time. As there are 4 color options, you will get a different color every time you pick up a marble up to the 4th time you pick up a marble. You must pick up a marble with the same color as one of the previous marbles on the 5th time as there are no other color options. If the worst case scenario persists, the process with repeat again until the 8th time you pick up a marble where you will now have 2 marbles each per color. On the 9th time you pick up a marble, you must pick up one of the existing color marbles, resulting in 3 marbles of a particular color.</p>