Re: More entry level stats

Hey lpg0005.

The first thing with the probability problems is to identify if a distribution exists that model the situation. You are looking at two successes of three trials and each trial is the same.

This corresponds to a Binomial distribution. You should look at the assumptions for this but basically they are that each trial has the same probability of a success or failure and all trials are independent where the distribution gives the probability of getting so many successes.

Re: More entry level stats

Well we got close to the correct answer using P(x)=q^(x-1)*p

P(3)=q^(3-1)*.8

But now that I am looking at it, I dont know how we arrived at 1.25, which we used as a z-score to get close the correct answer of .896

Re: More entry level stats

This distribution is not the Binomial one which fits the assumptions.

Consider finding P(X = 2) for P(X = x) = nCx p^(x) * (1-p)^(n-x). n = 3, p = 0.8 and P(X = 3) and add the two (since they are disjoint).