Given the letters a, b, c, d, and e.

Arranging the permutations of the letters a, b, c, d, and e in a dictionary:

To find: Rank of word debac in dictionary.

First comes, words starting from letter a = 4! = 24

words starting from letter b = 4! = 24

words starting from letter c = 4! = 24

words starting from letter d:

words starting from da = 3! = 6

words starting from db = 3! = 6

words starting from dc = 3! = 6

words starting from dea = 2! = 4

words starting from deb:

debac = 1

Rank of the word debac = 24 + 24 + 24 + 6 + 6 + 6 + 4 + 1

= 95

Hence the rank of the word debc in arranging the letters a, b, c, d, and e in a dictionary among its permutations is 95.