Answer: 0.660
Step-by-step explanation:
Denote [tex]B, P[/tex] as the event that you will be put in the basket-weaving course and the event that you will be put in the philosophy course, respectively. Denote [tex]A, X[/tex] as the event that you will get an A and the event that you will not get an A, respectively.
Using the addition rule and the multiplication rule:
[tex]P(A) = P(A \cap B) + P(A \cap P) = P(B) \times P(A|B) + P(P) \times P(A|P)\\ = 20\% \times 0.90 + 80\% \times 0.60 = 0.660[/tex]