6.19 Refer to Exercise 6.17. Calculate the following probabilities. a. P(A1 |B2) b. P(B2 |A1) c. Did you expect the answers to parts (a) and (b) to be reciprocals? In other words, did you expect that P(A1 |B2) = 1/P(B2 |A1)? Why is this impossible (unless both probabilities are 1)? 6.20 Are the events in Exercise 6.17 independent? Explain. 6.21 Refer to Exercise 6.17. Compute the following. a. P(A1 or B1) b. P(A1 or B2) c. P(A1 or A2)