1. Exchangeability with known model parameters: For each of the following three examples, answer: (i) Are
observations y1 and y2 exchangeable? (ii) Are observations y1 and y2 independent? (iii) Can we act as if the two
observations are independent?
(a) A box has one black ball and one white ball. We pick a ball y1 at random, put it back, and pick another
ball y2 at random.
(b) A box has one black ball and one white ball. We pick a ball y1 at random, we do not put it back, then we
pick ball y2.
(c) A box has a million black balls and a million white balls. We pick a ball y1 at random, we do not put it
back, then we pick ball y2 at random.

求助各位大神，非常感谢！