A random variable x has an Exponential distribution IT: f(x) => e" wherex 20 zero otherwise ; Al the distributional parameter ) 60. An Exponentially distributed random variable X has E X =1/1 and var X] = 1/12 Suppose there are three specialized components: widgets (W), sprockets (S) and pipes (P); whose functionality is each independently distributed as Exponential with distributional parameters A w= 2, A s= 1, and Ap = 0.25 respectively. A device, D, is built from these components using 3 widgets, 2 sprockets and 1 pipe. 16. The expected value of D is equal to: a. 7 2 b. 3 4 C. 6 d. 8 e. 6