Hey I have a very rookie question however, I havn't had statistics in a log time! I have a Log-normal distribution following ~(1,0.6^2). And I would like to find the probability that out of 15 stones, 5 of them weights more than 5 gram. I was thinking of a hypergeometric distribution? Other than that I'm not sure what method to use!
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Assuming independence of stone weights and the log-normal distribution is the distribution of each of these weights, after finding the probability of a single stone's weight being larger than 5 grams, i.e. $p=P(X>5)$, where $X\sim \text{Lognormal}(\mu=1,\sigma^2=0.6^2)$, it becomes a Binomial problem if the number of stones that weigh more than $5$ grams is called $Y$: $$P(Y=5)={15\choose 5}p^5(1-p)^{10}$$
if we're talking about exactly 5 of them being larger than 5 grams.
