0 votes 0 votes Q.1) find total number of 4 letter word which can be formed by using letter of word ALLAHABAD.in such a manner that there is exactly 2two letter are same and rest are different. BASANT KUMAR asked Oct 12, 2018 BASANT KUMAR 346 views answer comment Share Follow See 1 comment See all 1 1 comment reply Mk Utkarsh commented Oct 12, 2018 reply Follow Share $A \rightarrow 4$ $L \rightarrow 2$ $H \rightarrow 1$ $B \rightarrow 1$ $D \rightarrow 1$ AA _ _, 2 letters can be chosen in $\binom{4}{2}$ ways and then combination of all 4 letters can be permuted in $\frac{4!}{2!} = 12$ LL _ _, 2 letters can be chosen in $\binom{4}{2}$ ways and then combination of all 4 letters can be permuted in $\frac{4!}{2!} = 12$ total combinations = $\binom{4}{2} \times 12 + \binom{4}{2} \times 12 = 144 $ 1 votes 1 votes Please log in or register to add a comment.