申論題

1. Ben works as a computer operator at National Sun Yat-sen University. One evening he finds that fifteen computer programs have been subnitted earlier that day for batch processing. In how manry ways can Ben order the processing of these programs if

(c) he first separates the programs into four of top priority, eight of lesser priority, and three of least priority, and he wishes to process the fifteen programs in such a way that the top-priority programs are processed first and the three programs of least priority are processed last?