Let's complete the table by filling in the missing information for the given situation where Alexis picks a letter tile and then a number tile:
\begin{tabular}{|c|c|c|c|c|}
\hline & & \multicolumn{3}{|c|}{Letter Tile} \\
\hline & & A & B & C \\
\hline & 1 & A-1 & B-1 & C-1 \\
\cline{2-5} Number Tile & 2 & A-2 & B-2 & C-2 \\
\cline{2-5} & 3 & A-3 & B-3 & C-3 \\
\hline
\end{tabular}
Next, we need to determine the sample size of the event. The sample space is all possible combinations of drawing one letter tile (from A, B, and C) and one number tile (from 1, 2, and 3). Since there are 3 letter tiles and 3 number tiles, the sample size is:
[tex]\[ 3 \times 3 = 9 \][/tex]
So, the sample size of the event is [tex]\(9\)[/tex].
Thus, the final answers are:
Completing the table:
\begin{tabular}{|c|c|c|c|c|}
\hline & & \multicolumn{3}{|c|}{Letter Tile} \\
\hline & & A & B & C \\
\hline & 1 & A-1 & B-1 & C-1 \\
\cline{2-5} Number Tile & 2 & A-2 & B-2 & C-2 \\
\cline{2-5} & 3 & A-3 & B-3 & C-3 \\
\hline
\end{tabular}
The sample size of the event is [tex]\(\boxed{9}\)[/tex].
