Suppose that a student found an e-mail in the inbox folder. There is a 10% chance that it is a phishing e-mail (F) (i. e., P(F) = 0.1), and otherwise, it is a regular e-mail (F’). Based on the survey, it is known that the student will take one of the three options once he receives a phishing e-mail. The first is that there is a 60% chance that he will click "report phishing" (R) (i. e., P(R|F) = 0.6). The second is that there is a 30% chance that he will simply delete the email (D) without doing anything else (i. e., P(D|F) = 0.3), and the last is that he will read the e-mail and leave it in the inbox (L). On the other hand, if it is a regular e-mail, there is a 10% chance that he will click "report phishing" (R) (i. e., P(R|F’) = 0.1). There is another 10% chance that he will simply delete it (D), and otherwise, he will read it and leave it in the inbox (L). a) Draw a tree and find P(D), the probability that a randomly chosen e-mail is deleted. b) Suppose that an e-mail is reported as "phishing". Given that, what is the probability that it is actually a phishing e-mail?