The physical block size set in the file system is 5 12 bytes. Suppose a file control block has 48 bytes, and the symbol directory entries account for 8 bytes, of which the file name accounts for.

(1) symbol directory entries account for 8 bytes, the physical block size is 5 12 bytes, and the directory file contains 256 directory entries, so the physical block required to store the symbol file after decomposition is (8*256)/5 12=4.

(2) According to 4 found in (1), the average number of disk accesses is (1+4)/2+ 1=3.5.