Answer:
Explanation:
GIVEN: A bibliophile plans to put a total of seven books on her marble shelf. She can choose these seven books from a mixture of works from Antiquity and works on Post-modernism, of which there are seven each.
TO FIND: If the shelf must contain at least four works from Antiquity, and one on Post-Modernism, then how many ways can he select seven books to go on the shelf.
SOLUTION:
Total number of books available
As there must be at least
books on Antiquity and
on Post-modernism
Therefore,
when there are
Antiquity books and
on Post-modernism.
total ways of selection
when there are
Antiquity books and
on Post-modernism.
total ways of selection
when there are
Antiquity books on
books on Post-modernism.
total ways of selection
Total ways of selection are
Hence the total ways of selection such that there are at least
books on Antiquity and
on Post-modernism.