<p>I got a 690 on the math the first time I took it. Other than the weird crap that's regularly on the test like F of triangle = F of square, or whatever, the only types of problems that give me trouble are the 'combination' problems.</p>
<p>For example, there are 6 men. How many different combinations of handshakes can occur?</p>
<p>How do you quickly calculate that?</p>
<p>Another example would be, there are 5 different types of pants, 4 different types of shirts, and 3 different types of hats. How many different outfits are possible?</p>
<p>Person A shakes hands with 5 people.
Person B has already shaken with Person A, so he shakes hands with 4 other people.
Person C has already shaken with Person A and Person B, so he shakes hands with 3 other people.</p>
<p>etc etc. </p>
<p>5 + 4 + 3 + 2 + 1 = 15</p>
<p>For the second one, just multiply them together. 5 x 4 x 3 = 60 outfits</p>
<p>You just multiply for the second? Ok. That's what I would have guessed, but I really wasn't sure.</p>
<p>And about the first one...that's exactly how I usually do it (except I usually draw a pentagon because I'm a very visual person), but for problems larger than that (maybe it asks for twenty people instead of five) is there a faster way to do it, or is that the only way?</p>
<p>And about problems that give weirdly complicated patterns. The worst ones usually say something along the lines of, "Every odd number gets multiplied by negative two, and every even number is added by 3. Here is the sequence: 3, -6, -3, 6, ...What is the 50th number of this sequence."</p>
<p>Haha, you didn't get my point. The pattern you have is not the same as the college board one. the one they have is solvable, the numbers simply repeat themselves in certain orders, then u divide the the certain order number by the number they ask you to find, then look for remainder. Yours doesn't work like that :)</p>
<p>for an arithmetic progression: a, a+d, a+2d...,a+(n-1)d
summation of first n terms = (n/2) <em>[ 2a + (n-1)d] or also represented as (n/2)</em>[sum of first term and last term]</p>
<p>for a geometric progression: a, ar, ar^2, ar^3...ar^{n-1}
summation of first n terms = a [(r^n - 1)/(r - 1)]
and for infinite gp where r <1 .. the summation of the infinite series = a / 1-r</p>
<p>what effective ways are there to solve problems with variables? like this question on bb</p>
<p>"The price of ground coffee beans is d dollars for 8 ounces and each ounce makes c cups of brewed coffee. in terms of c and d, what is the dollar cost of the ground coffee beans required to make 1 cup of brewed coffee?"</p>