Assume that emails arrive at a company's inbox according to a Poisson process with

mean 19 per hour.

(a) When does the company expect the 11th email to arrive?

(b) When does the company expect the third email to arrive given that the second email arrived after 3 minutes?

(c) What is the standard deviation of the arrival time of the 14 email, given that the third email has not arrived yet after 2 minutes, but the second email has?