Assume that Y denotes the number of bacteria per cubic centimetre in a particular liquid and that Y has a Poisson distribution with parameter \lambda . Further assume that \lambda varies from location to location according to a gamma distribution with parameters \alpha and \beta , where \alpha is a positive integer. If we randomly select a location, what is the

(A) expected number of bacteria per cubic centimetre?

(B) standard deviation of the number of bacteria per cubic centimetre?