I'm confused on these arrangement problems:
9 different books are to be arranged on a bookshelf. 4 of these books were written by Shakespeare, 2 by Dickens, and 3 by Conrad. How many possible permutations are there if the books by Conrad must be separated from one another?
+2096 Total possible arrangements for the six books: 6! or 720
Places for Conrad's books are:
First book: 7 possible places
Second book: 6 possible places
Third book: 5 possible places
If we multiply that together, we'll get the total number of permutations!
So, our answer is 720 * 7 * 6 * 5 or 151200.
