A contractor is required by a county planning department to submit one, two, three, four or five forms (depending on the nature of the project) in applying for a building permit. Let Y- the number of forms required of the next applicant. The probability that y forms are required is known to be proportional to y+1, in other words the PMF of Y is given by p(y)- k(y +1) for y-1,...,5, and 0 otherwise.

(a) What is the value of k?

(b) What is the probability that at most three forms are required?

c) What is the probability that between two and four forms (inclusive) are required?

(d) Could p(y) = y2/50 for y-1, . . . ,5 be the PMF of Y? Explain why or why not.