Question

There are three copies of Harry Potter,four copies of The Last Symbol and five copies of The Secret of the Unicorn. In how many ways can you arrange these books in a shelf?

• A. $24500$
• B. $25550$
• C. $27720$
• D. none of these

Answer 1

Answer: (C)

$27720$

$3$ Copies : Harry Potter

$4$ Copies : The last symbol

$5$ Copies The secret of unicorn

Total number of books $=12$

Number of ways of arranging $=12!$

But there are $3,4,5$ similar books

Total number of ways

$=\frac{12!}{3!\times 4!\times 5!}=11\times 10\times 9\times 4\times 7=27720$