SOLUTION: a boy has 3 library tickets and 8 books of his interest in the library. of these 8, he does not want to borrow chemistry part 2, unless chemistry part 1 is also borrowed. in how ma

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Question 1120190: a boy has 3 library tickets and 8 books of his interest in the library. of these 8, he does not want to borrow chemistry part 2, unless chemistry part 1 is also borrowed. in how many ways can he choose the three books to be borrowed?
Answer by greenestamps(13203) About Me  (Show Source):
You can put this solution on YOUR website!


He can choose either

(1) chemistry part 1 and any 2 of the other 7 books: C(1,1)*C(7,2) = 1*21 = 21

or

(2) not chemistry part 1, and therefore not chemistry part 2, and any 3 of the other 6 books: C(6,3) = 20

The total number of ways he can choose 3 books is 21+20 = 41.