Question 821284
There are {{{26^4}}} possible words that could be formed that way, all equally probable.
The number of words that can be formed without repetition of letters is
{{{26*25*24*23}}} .
So in {{{26*25*24*23}}} out of {{{26^4}}} possible cases a word with no repetition of letter would be formed.
The probability that a word with no repetition of letter is formed is
{{{26*25*24*23/26^4=25*24*23/26^3=600*23/(2^3*13^3)=75*23/13^3=1725/2197=about0.785}}} (rounded)