A password is to be created at random by selecting 4 characters (with replacement) from the set {A, B,..., Z,0,1, .J.., 9}. Let X be the number of letters which are chosen for the password.
a. Find the probability mass function for the number of letters which are chosen.
b. Graph the probability mass function.
c. What is the mean number of letters which are chosen?
d. What is the standard deviation of the number of letters which are chosen? I
e. Find the cumulative distribution function.
f. Graph the cumulative distribution function.