Question 576097
I'll do the first one to get you started


A)


If the sums of all the individual probabilities add to 1 and each probability is positive (and less than 1), then this is a valid probability distribution. So let's add up the individual probabilities


P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4)


0.01 + 7/12 + 1/12 + 1/4


0.926666667


So the probabilities all add to 0.926666667, which is NOT 1.


So this is NOT a valid probability distribution.