logo

Ask Questions, Get Answers

 
X
 Search
Want to ask us a question? Click here
Browse Questions
Ad
Home  >>  CBSE XI  >>  Math  >>  Permutations and Combinations
0 votes

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

$\begin{array}{1 1}(A)\;907200\\(B)\;917200\\(C)\;926200\\(D)\;93630\end{array} $

Can you answer this question?
 
 

1 Answer

0 votes
Toolbox:
  • $n!=n(n-1)(n-2).....(3)(2)(1)$
Words starting with A are formed with the letters 2I's,2N's A,E,X,M,T,O
Numbers of words formed by these letters $=\large\frac{10!}{2!2!}$
$\Rightarrow \large\frac{10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1}{2\times 2}$
$\Rightarrow 10\times 9\times 8\times 7\times 6\times 5\times 3\times 2\times 1$
$\Rightarrow 907200$
Then the words starting with $E,I,M,N,O,T,X$ will be formed.
$\therefore$ Number of words before the first word starting with E is formed
$\Rightarrow 907200$
Hence (A) is the correct answer.
answered May 14, 2014 by sreemathi.v
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...