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Mar 13, 2022 at 22:05 comment added Kirsten So in summary, X is a Binomial RV and the 7 joint RVs are Bernoulli RVs.?
Mar 13, 2022 at 20:44 comment added Dilip Sarwate @Kirsten Well, yes, $X$ is indeed a binomial random variable, but you are insisting on finding a joint distribution of $X$ and some other random variable. The outcomes of the experiment (the data) are the 7 answers and the joint distributions that you ought to be seeking are the joint distribution of the 7 answers, and not the joint distribution with something else.
Mar 13, 2022 at 12:10 comment added Kirsten Thank you, but why is X not an RV? It looks like a "numerical description of the outcome of a statistical experiment." (though I now appreciate that the independent RVs in this problem must be the binary drink outcome ) britannica.com/science/statistics/…
Mar 12, 2022 at 14:44 comment added Dilip Sarwate @Kirsten Repeat as often as needed till you have memorized it: "X is not a random variable". There are 7 independent random variables representing the 7 answers; these random variables take on value Orange with (unknown) probability $p$ and value Grape with probability $1-p$. 4 of the answers are known to have value Orange and 3 to have value Grape. Before asking for the choices, we know that the joint probability that 4 of these 7 random variables will have value Orange and 3 will have value Grape is $\binom 74p^4(1-p)^3$. Repeat again: "X is not a random variable".
Mar 12, 2022 at 6:38 comment added Kirsten Thank you for the joint probability update. However looking at Wikipedia, a joint probability distribution involves two random variables. Surely we have only one here? that is X? Only X is mentioned in the Likelihood equation? Or is the other RV implied somehow as N-X? From your answer I guess it must be ... but surely N-X is not an RV indepentant of X? en.wikipedia.org/wiki/Joint_probability_distribution
Mar 11, 2022 at 21:17 history edited Dilip Sarwate CC BY-SA 4.0
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Mar 11, 2022 at 21:15 vote accept Kirsten
Mar 11, 2022 at 18:17 comment added Kirsten Thank you for clearing my confusion about the wording. I also asked about how joint probability applies here. Should that be a separate question?
Mar 11, 2022 at 15:00 history answered Dilip Sarwate CC BY-SA 4.0