A person working on a production line producen a number of items х in a day. This number is a Poisson random variable, where the mean number 2 of items produced each day is dependent on the person's energy level that day. That is 2 is itself a random variable and conditional on the value of 2 say = the distribution of X Is Poisson with parameter Assume that is a continuous exponential random variable with parameter Write a formula for the joint p.f/pdf. F(x,( ) of Х and