I'm wondering if there is an available command that can evaluate the number of terms required to produce a desired outcome.

Specifically, I am interested in determining the probability of a Poisson distribution, given the parameter (mean) value and the probability outcome. I can obtain the desired result using trial and error / brute force, but I am curious to know if there is a more efficient way. 

Suppose that, lambda = 2.6 and the cumulative sum of the probabilities is 95%. I know that I must add the first 6 terms for P(x) in the series (x=0,1, ..,5) to sum to 0.95. Each term ...  P(x=0)= 0.07, P(x=1)=0.19, and so on.

However, how can we know that desired 95% outcome can be determined from the first 5 terms without trial & error?

Is there a simple command to generate decimal numbers in a given range? 

For example, I wish to obtain a randomly generated number between, say ... -0.5 and 0.5.

Given a basic list of data, is it possible to extract the distribution type /  equation / probability density function?

I was looking to see if anyone has come across a Maple routine for a savings algorithm - specifically, Clarke and Wright. In fact, any classical savings heuristic would also be interesting.

Any guidance would be truly appreciated.

If binary constraints are imposed on an optimization problem and LPSolve presents a solution, is it possible to extract the variables that have zero or one assigned to them? This would be most useful if there are many variables, for example...

If a solution is returned that looks like ...

[x[001]=0, x[101]=1, x[201]=0, x[301]=1, ....], how can I filter those solutions that equal zero?

Thanks for reading!