There are 900 stocks from which you must pick 50 at random. What is the probability that you pick two in the top 30 return stocks? If necessary to assume a return distribution we can assume normal, but I don't think it is?
The hypergeometric distribution applies, though the binomial gives a very good approximation. The chance of exactly 2 top-30 stocks in a sample of 50 from a population of 900 is 27.6%. I think a more meaningful situation is the probability of at least two, and that value is 50.6%, The binomial gives 50.0%
Edit NTG has it but he has a 'math typo' for at least 2
