The number of 4 letter words (with or  Without meaning) that can be formed    from the eleven letters of the word EXAMINATION is__

EXAMINATION

No.of A’s 2
No.of I’s 2
No.of N’s 2
X $\to$ 1
E  $\to$1
M $\to$ 1
T’s $\to$1
O’s $\to$ 1
No.of different letters = 8
i) All different = $8_{p_4}$  = 1680
ii) 2same, 2 different

$3C_1\times 7C_2\times \frac{4!}{2!}=756$

iii) 2same, 2same

$3C_2\times \frac{4!}{2!2!}=18$
Total =1680+756+18=2454