How do price changes affect equilibrium? a. by assisting centrally planned economy b. by serving as a tool for distributing goods and services c. by limiting the market to people who have the most d. by preventing inflation or deflation from affecting the supply of goods

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?