SOLUTION: Betty has 20 different books.
A. If 4 books are selected from these 20 books, how many combinations are there?
B. Among the 20 books, 12 are classic novels, 6 are science fiction
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Question 1173584: Betty has 20 different books.
A. If 4 books are selected from these 20 books, how many combinations are there?
B. Among the 20 books, 12 are classic novels, 6 are science fictions, and 2 are reference books. If 7 classic novels, 2 science fictions, and 1 reference book are selected, how many combinations are there?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
a. This is 20C4=4845 ways
b. This will be: 12C7 for the first * 6C2 for the second*2C1 for the third
=792*15*2=23,760 ways.
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