Question 261290
In a library, 4 different english books, 2 different chemistry books and 3 different mathematics books are arranged on a shelf. Determine the number of different arrangements for the 9 books if the books on each subject must be kept together
------
1st: arrange the sets: 3! = 6 ways
2nd: arrange the books within each set: 4!*2!*3! = 24*2*6
-------------------
Total # of arrangements: 6*24*12 = 1728
=========================================
Cheers,
Stan H.