=+42. On a construction site, subcontractor A is responsible for completing the structural frame of a building. When this task is complete, subcontractor B then begins the task of installing electrical wiring and outlets. The following tables show estimated probabilities of completing each task in x days:

Framing time (days), x: 10 15 20 25 30 Probability, p1(x): .10 .20 .30 .30 .10 Wiring time (days), y: 5 10 15 20 Probability, p2(y): .20 .50 .20 .10