Correct Answer: (a + 2b + 3c + d)! / {a! (b!)2 (c!)3}
Explanation:
Total number of books = a + 2b + 3c + d . Since there are 'b' copies of each of two books, 'c' copies of each of three books and single copy of 'd' book.
Therefore, the total number of arrangements is = (a + 2b + 3c + d )! / {a! (b!)2 (c!)3}
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