17. One day, Captain Haddock receives a mysterious letter with a confusing paragraph. Captain Haddock and Tintin are investigating the matter. There are two possible suspects: Professor Calculus and Thomson $\&$ Thompson. Based on their past experience:
The probability that Professor Calculus sends a letter is $60 \%$, while the probability that Thomson $\&$ Thompson send a letter is $40 \%$.
When Professor Calculus sends letters, there is an $80 \%$ probability that the letter contains a confusing paragraph.
When Thomson \& Thompson send letters, there is a $5 \%$ probability that the letter contains a confusing paragraph.
What is the probability that the letter was sent by Professor Calculus? (a) 0.96 (b) 0.80 (c) 0.50 (d) 0.48
17. One day, Captain Haddock receives a mysterious letter with a confusing paragraph. Captain Haddock and Tintin are investigating the matter. There are two possible suspects: Professor Calculus and Thomson $\&$ Thompson. Based on their past experience:
\begin{itemize}
\item The probability that Professor Calculus sends a letter is $60 \%$, while the probability that Thomson $\&$ Thompson send a letter is $40 \%$.
\item When Professor Calculus sends letters, there is an $80 \%$ probability that the letter contains a confusing paragraph.
\item When Thomson \& Thompson send letters, there is a $5 \%$ probability that the letter contains a confusing paragraph.
\end{itemize}
What is the probability that the letter was sent by Professor Calculus?\\
(a) 0.96\\
(b) 0.80\\
(c) 0.50\\
(d) 0.48\\