Historically, 45% of visitors to the online store of XYZ company made a purchase. 40% of the visitors who made a purchase came to the online store through a web search engine. Also, 15% of visitors who did not make a purchase came to the online store through a web search engine. If a visitor comes to the online store through a web search engine, what is the probability that he or she will make a purchase? (Suggestion: To think through the problem, use a probability tree and "whether a visitor makes a purchase" as the first step to depict what is given. Use the Bayes Theorem to calculate the probability in question. You do not need to include the tree in your submission.). (4 points)