# gaussian distribution

1. ### Exercise on standard distribution

Hello, Suppose I want to calculate the probability for a user to pass from a basic to a premium account within the end of Q1 (i.e. end of march). I know that this is distributed with mean=50 days and st.dev=10 days, then the probability that a user pass to a premium account within the end of...
2. ### comparison with normal distribution truncated

Hello, I would to know how to calculate the probability that X > Y when Y is greater than a given value p (X and Y are random variable following normal distribution). I think that it is equivalent to caculate Y - X > 0 with X and Y are normal discutribution truncated at p. Thanks, Pascal
3. ### Conditional expectation of values higher than a threshold

Hi there! I'm having some hard time dealing with a question that hopefully will look trivial to someone here: Considering a gaussian distributed random variable: x~N(m,v) and a arbitrarily selected threshold t; what is the expected value for this variable if only x>t are considered...
4. ### Deriving Var from mu and two Ps

If I know the mean of a normal distribution and two probabilities F1=P(Z>z1) and F2=P(Z>z2), I should be able to derive the Var of the distribution, no? Can't figure how. Do I need to manipulate the CDF algebraically, or is there an easier (non-calculus intensive) way? In real terms, I know...
5. ### Gaussian Processes - Wiener process - The drunk particle

Hello, I recently read about Gaussian Processes (http://en.wikipedia.org/wiki/Gaussian_process) for non linear regression. I am not an expert but I found it quite interesting how to see for example a wiener process from the Gaussian processes perspective. An interesting example came to my...
6. ### How many measurements needed to distingish between two outcomes?

I have a historical dataset of about 500 measurements. Datapoints that turned out to indicate A or B, each have a distribution from which I computed mean and std. If I plot a histogram of these measurements, I have two semi-overlapping gaussian distributions. Those measurements that indicated A...
7. ### product of N normal distributions

We are given N normal functions, with means \mu_i, and variances \sigma_i^2, i in 1...N. I need to find a formula for the product of the N functions. The case N=2 is easy to find online: https://ccrma.stanford.edu/~jos/sasp/Product_Two_Gaussian_PDFs.html but I have found nothing regarding...
8. ### Probability that a set of numbers is non-random?

Hello, I'm wondering if anyone knows the answer to this: For a set of X numbers with a median of Y and a standard deviation of Z, where a set determined randomly according to a Gaussian distribution would have a median of 0, what is the probability that the median Y indicates that the set...