# Thread: Help Probability Question Urgent

1. ## Help Probability Question Urgent

Ok, there are 60 students in a class and there are 40 "good" students. A group of 10 students are sampled independently.

1. Calculate the probability that the group contains more good students than average.

Does this mean calculate P(X>20/3)?

2. The group actually contains 5 good students. Calculate the probability that the sixth student in the group is the theird good one.

2. I don't really understand the question.
What I think you need to do is figure out the probability that you choose 6, then 7 , then 8..., up to 10 good students. Then add them.
The underlying distribution is hypergeometric, where you have 40 nondefective (lol) and 20 defective students. Basically the old fashion urn scheme.