Stats help needed

Airlines sometimes overbook flights. Suppose that for a plane with 50 seats, 55 passengers have tickets. Define the random variable X as the number of ticketed passengers who actually show up for the flight. The probability mass function of X appears in the accompanying table. [Hound your answers to 4 decimal places. if needed.) nmmnmmmmmmm HX: 10.04 0.05 0.11 0.14 0.25 0.18 012 0.05 0.03 0.02 0.01 {a} What is the expected value of X? E {b} What is the variance of X? D [c] What is the standard deviation of X"? D {d} Determine the probability that X is within 1 standard deviation of its mean value. D