Suppose that X is a discrete random variable with possible values {1, 2, ...}, and probability mass function. pX(k) = c k(k+1) with some constant c > 0. (a) What is the value of c? Hint: 1 k(k+1) = 1 k − 1 k+1 . (b) Find E(X). Hint: Example D.5 could be helpful.

Question 1 of 10 2 points different groups of 50 graduates of an engineering school were asked the starting annual salary for their first engineering job after graduation, and the sampling variability was low. if the average salary of one of the groups was $65,000, which of these is least likely to be the average salary of another of the groups? o a. $64,000 o b. $65,000 o c. $67,000 o d. $54,000