Question 964708
How many ways can the letters A,B,C,D,E, and F be arranged in a row 4 at a time if
neither A nor C can be second and E must be third? Repetition is permitted. 
<pre>

Choose the 1st letter any of these 6 ways {A,B,C,D,E,F}

Choose the 2nd letter any of these 4 ways {B,D,E,F}

Choose the 3rd letters only 1 way {E}

Choose the 4th letter any of these 6 ways {A,B,C,D,E,F}

Answer: 6×4×1×6 = 144 ways

Edwin</pre>