Jean-Sébastien
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 Nov 7 comment How many tries to get at least k successes? @PaulAJungwirth Could you clarify what you mean by "Now suppose I want to know how many tries I need to achieve a given probability P′. How do I solve for n?" Do you want to know the probability that it takes $n$ trials to get $k$ succes? Nov 7 comment Find the distribution of $X$ given that $P(X=k)=\frac 23 (k+1)P(X=k+1)$ @F'OlaYinka I was just trying to illustrate user1551's point. I personnaly prefer to use $\mathbb{N}=0,1,2,\ldots$ as well Nov 7 comment Find the distribution of $X$ given that $P(X=k)=\frac 23 (k+1)P(X=k+1)$ @F'OlaYinka it depends on how you define it. some author will include it, some others won't Nov 7 comment Find the distribution of $X$ given that $P(X=k)=\frac 23 (k+1)P(X=k+1)$ Depends on what definition one has of $\N$ Nov 7 comment Find the distribution of $X$ given that $P(X=k)=\frac 23 (k+1)P(X=k+1)$ you mean $Pr(X=0)$ no? Nov 7 answered Find the distribution of $X$ given that $P(X=k)=\frac 23 (k+1)P(X=k+1)$ Nov 7 comment Does this change in this monotonic function affect ranking? @Diego I actually answered first, and we added the negative log almost simultaneously but it's alright with me ;) Nov 7 answered Does this change in this monotonic function affect ranking? Nov 7 comment Product of two independent stochastic variables $XY$ I think it is obvious, but there isn't really a standard notation so who knows Nov 7 comment Product of two independent stochastic variables $XY$ Is that binomial and Poisson? Nov 7 comment Is there an algorithm to determine whether a series converges? @Norbert, you should write out $\sin^2 n$ just to avoid the series being understood as $\sin(n^2)$ Nov 7 comment Dr. Math on factoring - mistake? Yeah I misread the word simultaneous, I'm sorry Nov 7 comment Dr. Math on factoring - mistake? @StevenStadnicki The way I understand it, he says that his functions are a counter example to the condition "there will be necessarily at least one complex ...". His function are not a counterexample of that. Perhaps I misinterpreted what was meant. Nov 7 comment Dr. Math on factoring - mistake? your $h(x,y)$ has no real zeroes Nov 7 comment Coefficients in series expansion of $\left(\frac{x}{1-x}\right)^3$ You should add the "^3" to the question's title Nov 7 answered How to calculate all combinations of string without repeat the same value Nov 7 comment Initial value problem: Solution blows up conditions Please consider editing your question with some work you have done and explain where exactly you are stuck Nov 7 reviewed Reviewed Prove that the centralizer is a normal subgroup. Nov 7 comment Proof of $\sum_{k=0}^n k \text{Pr}(X=k) = \sum^{n-1}_{k=0} \text{Pr}(X>k) -n \text{Pr}(X>n)$ @Sepehr If you look at it carefully, it only appears once. The second summation is of index $i$, while the inside sum has not $i$, just a $j$. this is why it becomes $j\times P(X=j$) in the second line. Try writing the first two sums in a array, lines being on $j$ and column on $i$. First line sums each line while second sums each column. I'll edit if you can't get it. Nov 7 comment Expectation of a positive integer? see this thread math.stackexchange.com/questions/231832/…