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Question
A boy has 3 library tickets and 8 books of his interest in the library. Of these 8, he does not want to borrow Mathematics Part II, unless Mathematics Part I is also borrowed. In how many ways can he choose the three books to be borrowed?
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Solution
Let us make the following cases:
Case (i): Boy borrows Mathematics Part II
Then he borrows Mathematics Part I also.
So the number of possible choices is 6C1 = 6.
Case (ii): Boy does not borrow Mathematics Part II
Then the number of possible choices is 7C3 = 35.
Hence, the total number of possible choices is 35 + 6 = 41.
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