Answer:
63/380
Step-by-step explanation:
Initially,
# of Mysteries, M = 9
# of Biographies, B = 7
# of Sci. Fiction, S = 4
Total number of books = 9 + 7 + 4 = 20 books
P (first book selected is biography) = 7/20
After selecting 1 biography book,
# of Mysteries, M = 9
# of Biographies, B = 7 - 1 = 6
# of Sci. Fiction, S = 4
Total number of books remaining = 9 + 6 + 4 = 19 books
P (second book selected is a mystery) = 9/19
Hence (P first book is biography and 2nd book is mystery)
= (7/20 )(9/19)
= 63/380
