<p>can everyone post a summery of the concepts and a strategy(formula) that hits these type of question.</p>
<p>LOGICAL Problems
Rate
Solving for multiple variable
Polygons
counting problems</p>
<p>Maybe you could post some specific problems from each type or something. Otherwise it is hard to give advice.</p>
<p>ok, on counting problems , how do u find the nth number?</p>
<p>For an arithmatic sequence when A is the starting number of trhe sequance, n is the nth number, and D is the ammount you add each time use this formula: A+(n-1)D</p>
<p>For a geometric sequence where B is the starting number, R is the ammount you multiply it each time, and n is the nth number, use this formula: B(R)^(n-1)</p>
<p>If you want something better, post an example.</p>
<p>I am also having trouble with rates. I saw a formula in these forums: (2)(Speed1)(Speed2)/(Speed1+Speed2). Can someone explain to me why this works? Is there a specific prep book that goes over difficult problems such as these? Thanks.</p>
<p>Do you mean sequence/series problems? Well if you do, you have to find a formula based on the relationship between the terms and the first term in the series. On the SAT there are 2 different types of series, arithmetic and geometric.
Arithmetic series are formed by adding a certain value to the preceding term. For example 2, 5, 8, 11, 14, 17, 20, ...An. The formula for this would be An = 2 + (n-1)(3)
To find the nth term you would just plug n into the equation.
The general formula for arithmetic series is An = A1 + (n-1)(d) where d is the difference between consecutive terms, A1 is the first term, and An is the nth term.</p>
<p>In geometric series, there is a common ratio that gets multiplied by the previous term to get the next term. For example 1, 2, 4, 8, 16, 32,...An. the common ratio is 2 for this one. The formula for geometric series is An = A1<em>r^(n-1) where r is the ratio between consecutive terms. So the formula for the previous series would be An = 1</em>2^(n-1).</p>
<p>You might also be asked to find the sum of a series of numbers.
The sum of an arithmetic series is found by this formula: Sn = (n/2)(A1 + An)</p>
<p>The formula for the sum of a geometric series: Sn = A1(1 - r^n)/(1-r)</p>
<p>And there is probably no chance of this type of question...but the formula for the sum of an infinite geometric series is S = A1/(1-r)</p>
<p>Can someone please post an SAT question where they had to use the Arithmatic/Geometric sequence/series formula? I never thought of using it on the SAT before.</p>
<p>I had one on my (May) SAT. I believe the question was something like this: The first term is 1/10000, the second term is 1/1000, the third term is 1/100, etc. with each term found by multiplying the previous term by 10. What is the 100th term in this series?</p>
<p>Oh man... So let's see... that's a ...</p>
<p>(1/10000)(100)^(100-1) = .00....1</p>
<p>Really? I got 1e95.</p>
<p>T100 = T1 * R ^ (N - 1) = 1/10000 * 10 ^ 99) = 1e95</p>
<p>this one must have been on the experimental section in May, because I didn't have it. but I've never seen a series/sequence problem that required the formula. If you know it already, great, but otherwise the trick is to quickly realize that the fifth term would get you to 1, so the answer is obviously 1e95. The answer choices also would have given you an immediate clue as to the direction the problem is going.</p>
<p>I think it is risky to try to deal with problems like these using the formulas, because the CB can easily throw a twist into the problem that will mess you up if all you know how to do is rotely apply a formula. For example, a "repeating pattern" series problem is much more common than a direct arithmetic or geometric sequence problem. For repeating patterns problem there is no formula per se; you need to find the pattern and how many times it repeats, then think about the concept of a remainder.</p>
<p>It was not in an experimental section. My experimental section was CR. There are multiple versions of the test on each test date, not just varying experimental sections.</p>
<p>theoneo you are correct.</p>
<p>Aw I kinda wish that was on your experimental. Maybe I'd have gotten it on my SAT this fall :P.</p>
<p>sorry flip. I guess that's true if you're referring to the Sunday test (for people who can't test on Saturday for religious reasons). but I thought that otherwise there is only one test (varying experimental sections of course). I could be wrong though. Maybe it is only the dates when the test is released (like the March tests) that there is only one test.</p>
<p>the other possibility is that I had that problem in May and I just don't remember it.</p>
<p>Sorry theoneo. For some reason I saw a - or something infront of my 1.</p>
<p>That's because its 2:30 in the stupid morning. v-v Im going to bed.</p>
<p>Just don't memorize a lot of stupid formulas. Like for rates, think about it in real life terms. When x amount of time passes, y amount of liquid is in the bucket. Use that stepping logic and all the problems will be easy.</p>
<p>I save formulas in my calc so I don 't have to memorize them.</p>
<p>2400SAT, you might be right about the March SAT, but I am positive there are different versions of the SAT on the other dates (well at least in May), not on Sunday. I asked people about some of the Math problems and Writing questions, and only a few people I know had the same test. That really ****ed me off because my math section was hard, but I heard others say theirs was easy.</p>
<p>Ok I pose this question to all of you. I am a rising sophomore and my practice math score is around 650. I want to increase that to a minimum 700+. If I prep three hours a day for apporximately 1 month can I achieve this goal. If not, how long do I need to prep to increase my score. Thanks.</p>
<p>Dude, if you prep for 90 hours and you don't raise your score from 650 to 700+.....</p>
<p>I bet a test prep company would love to hear from you. They'd try to sell you the platinum package. </p>
<p>Seriously, I don't mean to be rude, but it should NOT take you that much time. Going from 650 to 700+ means getting as few as 3-4 more questions right. </p>
<p>Take a look at the xiggi method and other good advice on these boards for students already scoring fairly high, and you should be able to get the score you want much more efficiently than you think. Clearly, motivation shouldn't be a problem for you.</p>