If the different permutations of all the letter of the word EXAMINATION are listed as in a dictionary, how many words are there in this list before the first word starting with E?
If the different permutations of all the letter of the word EXAMINATION are listed as in a dictionary, how many words are there in this list before the first word starting with E?

In dictionary words are listed alphabetically, so to find the words

Listed before $E$ should start with letter either $A,\;B, \;C \;or \;D$

But the word $EXAMINATION$ doesn`t have $B,\;C \;or \;D$

Hence the words should start with letter $A$

The remaining $10\;places$ are to be filled by the remaining letters of the word $EXAMINATION$ which are $E,\; X,\; A,\; M,\; 2N, \;T,\; 2I, \;0$

Since the letters are repeating the formula used would be

NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 45

Where $n$ is remaining number of letters \[{{p}_{1}}and\text{ }{{p}_{2}}\] are number of times the repeated terms occurs.

NCERT Solutions for Class 11 Maths Chapter 7 Permutations and Combinations Image 46

The number of words in the list before the word starting with $E$

\[=\text{ }words\text{ }starting\text{ }with\text{ }letter\text{ }A\text{ }=\text{ }907200\]