Recent content by bob j

the gen. chi square looks quite different than the chi square distribution. It's not just scaling, at least from what i can understand

why did they bother deriving the generalized chi square distribution then?

I read this article about non central chi square distribution http://en.wikipedia.org/wiki/Noncentral_chi-square_distribution in practice, if I have a sum of X_i^2, where X_i is gaussian with mean \mu_i and std \sigma_i what would be the pdf of the sum? In the article the assume you have...

not really.. could you possibly give me a simple example?

Hi All, suppose I have something like x^x^x^x where x is an integer. Is there any trick to figure the last digit of the result? Thank you

Hi All, does anyone know of any greedy or suboptimal algorithm to obtain harmonious coloring on a graph?

could you possibly tell me how to derive that mathematically? It is not clear to me why knowing one side of the pancake is brown is not equivalent to knowing that one child is a boy. Thanks a lot

I have a question about two puzzles that seem similar to me, but I have different answers to them. One is the following: You have a hat in which there are three pancakes: One is golden on both sides, one is brown on both sides, and one is golden on one side and brown on the other. You...

I don't see that

on a sheet of paper, you have 100 statements written down. the first says, "at most 0 of these 100 statements are true." the second says, "at most 1 of these 100 statements are true." ... the nth says, "at most (n-1) of these 100 statements are true. ... the 100th says, "at most 99 of these...

Let's say there is a file composed of n lines. I do not know the number of lines in advance. I wish to pick k random lines from the file, with one read only (without storing the lines in memory and then doing the rest)...

I have a list of n items. My goal is to pick k (assume k < n) items from the list such that each one of them as probability 1/n of being chosen. Would it be possible to accomplish this without knowing n, in one reading? thanks

Hi All, I was wondering if anyone could give me a suggestion to solve this "With one die, suppose in a round, you earn the amount of dollars equal to the value of the upwards face of the die. (eg. you earn $6 if you roll a six.) Now also suppose after your first roll, you are given the...

Hello, I wanted to know if any of you people know where I can find on the web two particular kind of puzzles (possibly with solutions): 1) series of numbers 2) grids with symbols, dots or objects in each cell except one, which is the one you are supposed to complete based on the rest of the...

never mind, I solved it ;)