Posted: March 28th, 2017

f(x) = r N-r

I can do the Hyper formula f(x) = r N-r
x n-x divided by N
n
but I cant figure out all my needed numbers from the problem.
Problem states 20% enrolled in training dropped out without completing their training and the likelihood of dropping out is the same for all participants.
If new group had 20 whats the expected value and standard deviation for number of drop outs? Usually E(x) = np, but I’m not sure if 0 is my p and 20 is my n.
Whats the probability that no one will drop out?
According to the book, x= probability of x successes in n trials, n= number of trials, N = number of elements in the population, r= number of elements in the population labeled success.
I think x = 0, n = 20, but I don’t know the N for my population size or the number for the r.
Can you help?