Problem
There are two bags, each containing 100 ping-pong balls. Bag A contains 100 red balls and no black balls, and bag B contains 20 red and 80 black. You are blindfolded and reach into a bag. There is a .5 probability it is bag A and a .5 probability it is bag B. You draw a red ball. What is the probability that you drew the ball from bag A?
The response should include a reference list. Double-space, using Times New Roman 12 pnt font, one-inch margins, and APA style of writing and citations.