Three boxes \( B_1, B_2, B_3 \) contain white, black, and red balls as follows:
\[
\begin{array}{|c|c|c|c|}
\hline
& \textbf{White} & \textbf{Black} & \textbf{Red} \\
\hline
B_1 & 2 & 1 & 2 \\
B_2 & 3 & 2 & 4 \\
B_3 & 4 & 3 & 2 \\
\hline
\end{array}
\]
A die is thrown:
- Box \( B_1 \) is chosen if the die shows 1 or 2
- Box \( B_2 \) is chosen if the die shows 3 or 4
- Box \( B_3 \) is chosen if the die shows 5 or 6
A ball is drawn at random from the selected box.
the ball drawn is red, find the probability it came from box \( B_2 \):