<ol>
<li><p>Meredith has a red hat, a blue hat, and a white hat. She also has three sweaters-one red, one blue, and one white. Meredith wants to wear a red, white, and blue outfit consisting of one hat, on sweater, and one pair of jean. How many different possibilities doe she have?</p></li>
<li><p>Any two points determine a line. If there are 6 points in a plan, no 3 of which lie on the same line, how many lines are determined by pairs of these 6 points?</p></li>
</ol>
<p>For the first question I solved it by multiplying 3<em>2</em>1 = 6 (3 choices, then 2 choices, then 1 choice).</p>
<p>Why does this not work for the second question? Instead of multiplying, I have to add 5+4+3+2+1 = 15.</p>