1. Based on past records, a manufacturer's repair facility for digital cameras has observed the following: 50% of all cameras sent to the facility have only an electrical problem (E), 30% have only a mechanical problem (M), and 20% have both an electrical and mechanical problem (B). Among the cameras with only an electrical problem, 70% are repaired and returned to the customer (R), while the remainder cannot be repaired and must be replaced with a new camera (N). Among the cameras with only a mechanical defect, 90% are repaired and returned, with the remainder being replaced with a new camera. And among the cameras with both an electrical and mechanical problem, 20% are repaired and returned, with the remainder being replaced with a new camera.

(a) Of all the cameras that are sent to the repair facility, what PERCENTAGE end up being replaced with a new camera (N)?

(b) Of all the cameras that are sent to the repair facility, what PERCENTAGE have only one defect and are repaired and returned to the customer?

(c) If a randomly selected camera at the repair facility is found to be in need of replacement with a new camera (N), what is the probability that this camera has both an electrical and mechanical problem (B)?