I am having difficulty trying to get correct answer for the following problem:
Mr. Smith has 8 master keys that unlock several chests. Only one master key will unlock a given chest. 40% of these chests are usually left open, what is the probability that Mr. Smith can unlock a specific chest if he selects 3 master keys at random?
My attempt: I have a feeling this maybe totally wrong.
I am pretty sure it is a binomial distribution problem
P(X=3) = (8C3)(.4^3)(.6^5) = 3.66176