Three tables listed below show random variables and their probabilities. However, only one of these is actually a probability distribution.

a.?Which of the above tables is a probability distribution?b.?Using the correct probability distribution, find the probability that?x?is:1.?Exactly 75.2.?No more than 50.3.?More than 25.c. Compute the mean, variance, and standard deviation of this distribution.

P(x) P(x) P(x) 25 25 0.1 25 0.5 -0.6 0.2 50 0.7 50 50 0.3 75 0.2 75 0.1 75 0.1 0.4 0.1 100 100 100 0.1