<p>I’ll help with a few…</p>
<p>For the second one, see this thread: </p>
<p><a href=“http://talk.collegeconfidential.com/sat-preparation/1180319-sat-math-help.html[/url]”>http://talk.collegeconfidential.com/sat-preparation/1180319-sat-math-help.html</a></p>
<p>For the marbles: 4 white and 5 black…</p>
<p>It’s 4/9 x 3/8 + 5/9 x 4/8 </p>
<p>The first product is the probablilty of drawing white followed by white. The next product is for drawing black followed by black. I don’t understand/agree with the answer you gave.</p>
<p>For the 7 books…If two of them have to be together, then think of them as one unit. So that gives you 6 “units” to arrange (5 books and one book-book set). That’s where the 6! comes from. But then you have to double the answer because you get a new arrangement if you take the two books that make a unit and reverse them.</p>
<p>As for the 5 cards, this is a retread of an old blue book question. Quickest way is to start with card C, for which there are 3 places. Then, the next card you place has 4 spots available. Then the next one has 3, then 2, and the last card has 1 spot left. So to get the answer, multiply 3x4x3x2x1.</p>
<p>OK, one more: the circle one – just use the distance formula to check how far each point is from the origin. Only one is less than 10 away.</p>