15. A computer consulting rm presently has bids out on three projects. Let Ai  {awarded project i}, for i  1, 2, 3, and suppose that P(A1)  .22, P(A2) 

.25, P(A3)  .28, P(A1  A2)  .11, P(A1  A3) 

.05, P(A2  A3)  .07, P(A1  A2  A3)  .01.

Express in words each of the following events, and compute the probability of each event:

a. A1  A2

b. A1  A2 [Hint: (A1  A2)  A1  A2]

c. A1  A2  A3

d. A1  A2  A3

e. A1  A2  A3

f. (A1  A2)  A3