An urn contains 4 defective and 8 non-defective balls. A second urn contains 2 defective and 6 non defective balls. A ball is drawn from one of the urns selected at random. Find the following...

Extracted text: An urn contains 4 defective and 8 non-defective balls. A second urn contains 2 defective and 6 non defective balls. A ball is drawn from one of the urns selected at random. Find the following probabilities: (a) That the ball drawn is defective. (b) That the ball drawn is non-defective. (c) That a ball is drawn from the first urn, given that it was a defective ball.