Catherine Posted May 7, 2010 Share Posted May 7, 2010 My ds, who is normally pretty good at math, si reviewing for the SAT 2 in Math 2. One of the first problems in the College Board review book is completely unrecognizeable to me: it'e number 16 on page 106, if you have the book. It's under the "Number and Operations" section and is about choosing 2 out of a group of 6 and 4 out of a group of 8. The solution has a notation I don't recognize that looks like a fraction without the line between the numbers, enclosed in parentheses. Ds says it's "six choose two". Where would I find a resource for reviewing this kind of math? Quote Link to comment Share on other sites More sharing options...
mpcTutor Posted May 7, 2010 Share Posted May 7, 2010 My ds, who is normally pretty good at math, si reviewing for the SAT 2 in Math 2. One of the first problems in the College Board review book is completely unrecognizeable to me: it'e number 16 on page 106, if you have the book. It's under the "Number and Operations" section and is about choosing 2 out of a group of 6 and 4 out of a group of 8. The solution has a notation I don't recognize that looks like a fraction without the line between the numbers, enclosed in parentheses. Ds says it's "six choose two". Where would I find a resource for reviewing this kind of math? The same notation that you are referring to can be written as C(n.r) or specifically C(6,2) and C(8, 4) for ease of typing (which is accepted method of representation in many textbooks) C(n.r) means number of distinct combination (or groups) possible when each group contains r things out of n things. Please feel free to write back if you need detail answer. But in short, C(6,2) = 6!/[2!(6-2)!] = 15 C(8,4) = 8!/[4!(8-4)!] = 70 Thus, total ways = 15 x 70 = 1050 The topic to look for further information on notation is "Permutation and combination from pre-calculus" . We are currently registering students for online class for Pre-Calculus at our website. Sample of topic/chapter wise DVDs may also be available. Please send your request if you are interested. Best regards. MPCTutor www.mpclasses.com Contact for Additional Info --------------------------------------------------------------------------- AP Calculus, AP Physics, Singapore Math Grades 7-12 --------------------------------------------------------------------------- US Central Time: 11:06 AM 5/7/2010 Quote Link to comment Share on other sites More sharing options...
Kathy in Richmond Posted May 7, 2010 Share Posted May 7, 2010 Khan Academy has some videos explaining combinations. Scroll down to the Probability section and look through the topics. The videos through the combinations topics might be helpful on this test. ~Kathy Quote Link to comment Share on other sites More sharing options...
Catherine Posted May 7, 2010 Author Share Posted May 7, 2010 Thank you both so much!! Quote Link to comment Share on other sites More sharing options...
Belacqua Posted May 7, 2010 Share Posted May 7, 2010 The Art of Problem Solving website has a wiki with explanations of mathematical concepts. If you do a search for "combination" on that site, you might find some helpful information, as well as some practice problems. Quote Link to comment Share on other sites More sharing options...
MyThreeSons Posted May 8, 2010 Share Posted May 8, 2010 BTW, many scientific calculators have a button which allows you to put in the two numbers and it gives you the answer. Quote Link to comment Share on other sites More sharing options...
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