A company provides equipment maintenance services to a variety of organizations. The timeliness of service depends on the general availability of spare parts. Let denote the unit-less measure of spare parts availability at the time a service call is received where . A larger value of implies greater spare part availability. Let denote the time required to complete service where is measured in hours. The joint PDF of and is given by
(a) Construct the joint of and .
(b) Determine the marginal PDFs of and .
(c) What is the covariance of and ?