Answer:
[tex]24\ passwords[/tex]
Step-by-step explanation:
[tex]Total\ available\ characters=4(a,b,c,d)\\\\ We\ want\ to\ choose\ 3\ of\ them.\\Here\ order\ matters\ (for\ example\ abc\ and\ acb\ are\ two\ different\ passwords) \\Hence\ we\ have\ to\ take\ permutation\ to\ count\ total\ possibilities.\\\\Total\ number\ of\ passwords=^4P_3\\\\Total\ number\ of\ passwords=\frac{4!}{(4-3)!}\\\\Total\ number\ of\ passwords=\frac{4!}{1!}\\\\Total\ number\ of\ passwords=24[/tex]
