SNYP40A1

Answer is C(52,5) - C(13,5)*C(4,1)^5

How many ways are there to choose 2 cards of the same rank in 5-card poker? There are 13 ranks of 4 suites to give 52 cards total. Note, the answer is not C(4,2)*C(50,3) due to repetition.

Get an integer where each digit, 0-9, is used exactly twice. However, the number cannot start with a 0. How many numbers meeting this requirement are there?

I got something very close to that, but not quite the same. I reasoned to first compute all combinations ignoring the leading 0 requirement, and then compute the number of combinations of 0 followed by 19 digits. Subtract the second from the first. So our answers differ by one term. I came up with (20! - 19!)/(2^10).

My friend who is preparing for his GRE asked me this question. I don't know how to answer it. Might be a good review question. How many decimal numbers without leading 0s use each digit exactly twice? My thoughts are to start with 20! and then divide out the duplicates which might be 2^10...then somehow the leading 0 part needs to be taken care of.

Thanks for the note. Trouble is that I can use google for searching most things...I used it for finding answers to GRE math questions by simply typing in the question. However, for mathematical proofs, there is no search function. And what I am trying to derive is not that complicated, for example: Say I want to prove that... The gradient with respect to A of the trace of ABA'C = CAB + C'AB' Or the gradient of the determinant of A = the determinant of A * the inverse of A'. (Where ' means "transpose") Those are some examples. I don't think I actually need to understand the math in order to apply it, but to apply it well and really understand what I am doing, I suspect that there is no substitute.

I have some linear algebra questions and I figure that someone on here knows of a good math forum where they can be asked. Or any good place for downloading free ebooks on Math would be great as well. Anyone know of some good resources? I am trying to teach myself machine learning and I need to improve my ability to derive proofs. I already watched the linear algebra lectures at MIT open courseware, those are really good. Still have some questions though.

I took my GRE a long time ago, but when I stumbled upon this page, thought it might be useful to those prepping for the math section: Calculus Without Calculus — Solving Geometric Calculus Problems With Simple Vector Geometry

It depends a lot on the rest of your application. If you are a domestic student, those scores should not matter too much depending on the school that you are applying to. Give yourself a lot of time to prepare, you have to learn the test.

haha, nice comments arc. I went to UW for undergrad and it is a nice campus in a nice city. I live in Oregon currently and Washington is definitely a better place to live, both for school and after school.

ETS does not care about service because, like the government, they don't have to. They have a monopoly on the test market.

I took the GRE exactly 1 year ago today. Thought I would stop by and see how things have changed. Not surprisingly, I remember seeing this same question before and it should be archived on these forums. But I will give the same response that I once gave before: Consider each that each pair of numbers defines the sides of a rectangle. When you multiple the sides of a rectangle, you get area. For a fixed perimeter, when is the area maximized? When the sides are equal - the case of a square.

I really like UW, it's a great place. I went there for undergrad and they have a new CS building that's really neat. Anyway, I looked at the profiles of some of the admitted students, you either have to have a ton of research experience and excellent stats to get in.

Well, it was exactly one year ago today when I took the GRE. Long story short, I applied to three very good schools, but did not get in anywhere. My background is in Electrical Engineering and I applied to some Bioengineering programs / synthetic biology. So that was kinda bad, probably because I had no experience in biology and minimal chemistry. Anyway, not to repeat my mistakes, I want to apply to some programs in Computer Science. Unlike last year, I am absolutely sure CS is the field for me. Over the past year, I have taken some programming / data structures courses and I am well on my way to obtaining the undergraduate equivalent to a CS degree (EE is pretty close, just need to get the core CS courses). Basically, I need 3 or 4 more classes to get there fully: discrete structures, algorithms, and theory of complexity. So hopefully, I can convince the departments that I am applying to that I at least have some background in the area of which I am interested. I also have taken a course in compilers, data networks, and of course the EE-side: logic design and electronics. Anyway, to get to the point, I am not sure about how to write my statement of purpose. I wrote one last year, but obviously it must not have been good enough. I think I am most interested in systems or artificial intelligence, but I don't really know how to explain my interest. I like it better than other stuff I have learned. I have read up on AI, but mostly want to do it because of what I can do with the knowledge - I like automation and using computers to make life easier for humans -- that's really my core interest. I have some undergraduate research in the area of autonomous navigation, but that was really a "lego's project". It did not involve any real core AI concepts. Anyway, I have good undergraduate grades from a good university and a pretty good GRE 1450 (790q, 660v). Not really sure how to approach the statement of purpose or where I should apply. Any suggestions. Sorry, that came out longer than I expected.

Rapidshare has been down for a while now. Tripod still works.