Some Math Questions

Test Preparation SAT Preparation
1

<h1>12, medium. I know the solution to these problem types are really simple, but I can never remember exactly what to do... I can never think about these ones the right way.</h1>

<p>There are 25 trays on a table in the cafeteria. Each tray contains a cup only, a plate only, or both a cup and a plate. If 15 of the plates contain cups and 21 of the trays contains plates, how many contain both a cup and a plate?</p>

<h1>18, hard.</h1>

<p><a href="http://img87.imageshack.us/img87/1820/screenshot003xm3.jpg%5B/url%5D"&gt;http://img87.imageshack.us/img87/1820/screenshot003xm3.jpg&lt;/a&gt;&lt;/p>

<p>Hate these types too.</p>

<p>If you know of any similar problems, let me know please!</p>

<p>Thanks.</p>

2

<p>I got 70/3 for the 2nd one. Don't know if it's right though.</p>

3

<p>here is the method for the first one...</p>

<p>Group1 + Group2 - Total = both
15 + 21 - 25 = 11</p>

4

<p>18 is trivial.
PT=2/5 * PS
assign values.
PT=2 PS=3.
area of triangle is 7 so
RS = 14 /3 </p>

<p>(3+2) * 14 /3 = 70 /3</p>

5

<p>cool, looks like I got it right</p>

6

<p>Bah. I knew 14 was incredibly simple.</p>

<p>Thanks.</p>

7

<p>Here are 4 more that have me confused:</p>

<p><a href="http://img225.imageshack.us/img225/9739/llie5.jpg%5B/url%5D"&gt;http://img225.imageshack.us/img225/9739/llie5.jpg&lt;/a&gt;&lt;/p>