Trouble understanding PMF tables

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Longines
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Hello all, I'm back with another basic probability question:

View attachment 3283

I know that it involves Bayes theorem somewhere, but I don't understand this question at all!

Note: This isn't an assignment question or anything like that, it's just a textbook question that I need help with.

Thank you
 
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  • Typeset problem statement: discrete random variable U with PMF table, values u = 1/4, 1/2, 3/4 and p_U(u) = 1/4, 1/2, 1/4; X is binomial with parameters (2, u) conditionally on U = u; parts (a) to (c) ask for P(X = 1 | U = u), P(X = 1), and P(U = 1/2 | X = 1).
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Hi,
Let's kick-off with question $(a)$. We have given that $X$ is a random variable such that conditionally on $\{U=u\}$, $X$ is binomial with parameters $(2,u)$.

Do you know the binomial distribution? If you do, you only need to apply it's PMF for question $(a)$.

Hint for question $(b)$: law of total probability.