Please answer these two questions

Three tables listed below show random variables and their probabilities. However, only one ofthese is actually a probability distribution. A B C x P(x) 1: P(x) x P(x) 25 0.2 25 0.2 25 0.2 50 0.3 50 0.3 50 0.3 75 0.4 75 0.4 75 0.4 100 0.3 100 0.1 100 0.5 a. Which of the above tables is a probability distribution? (Click to select) v b. Using the correct probability distribution, find the probability that x is: (Round the final answers to 1 decimal place.) 1. Exactly 75 = 2. No more than 50 = 3. More than 25 = c. Compute the mean, variance, and standard deviation of this distribution. (Round the final answers to 2 decimal places.) 1 . Mean u 2- Variance 02 3. Standard deviation 0 Exercise 5-37 It is estimated that 0.5% of the callers to the billing department of a local telephone company will receive a busy signal. What is the probability that of today's 1080 callers at least 5 received a busy signal? Use the poisson approximation to the binomial. (Round the final answer to 4 decimal places.) Probability