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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/…
Nov
7
revised Proof of $\sum_{k=0}^n k \text{Pr}(X=k) = \sum^{n-1}_{k=0} \text{Pr}(X>k) -n \text{Pr}(X>n)$
added 106 characters in body
Nov
7
comment Proof of $\sum_{k=0}^n k \text{Pr}(X=k) = \sum^{n-1}_{k=0} \text{Pr}(X>k) -n \text{Pr}(X>n)$
I was proving the wrong thing, when I saw your edit :P
Nov
7
answered Proof of $\sum_{k=0}^n k \text{Pr}(X=k) = \sum^{n-1}_{k=0} \text{Pr}(X>k) -n \text{Pr}(X>n)$
Nov
6
revised Where to begin in approaching Stochastic Calculus?
added 2 characters in body
Nov
6
answered Where to begin in approaching Stochastic Calculus?
Nov
6
comment Where to begin in approaching Stochastic Calculus?
What I meant was, what kind of probability have you done
Nov
6
comment Where to begin in approaching Stochastic Calculus?
When you say probability, is it the measure theory approach or the classical one?
Nov
5
awarded  Citizen Patrol
Nov
5
comment Probability of A wins the game
Many problems in probability cna be solved with symmetry. You just need to see it. Sometimes the long road gives other insight though
Nov
5
revised Probability of A wins the game
added 17 characters in body
Nov
5
comment Probability of A wins the game
@did So I was right :P. Your shortcut is quicker though
Nov
5
comment Probability of A wins the game
Now one of us screw up, probably me on this early morning... gonna re check after my class
Nov
5
answered Probability of A wins the game
Nov
4
revised Calculus: $\arccos(x)$ - task problem
added 967 characters in body
Nov
4
comment Calculus: $\arccos(x)$ - task problem
I'm working on something for you
Nov
4
revised Calculus: $\arccos(x)$ - task problem
Fixed latex and retagged
Nov
4
suggested approved edit on Calculus: $\arccos(x)$ - task problem
Nov
4
answered Calculus: $\arccos(x)$ - task problem