To diagnose colorectal cancer, the hemoccult test is conducted to detect occult blood in the stool. For symptom-free people over 50 years old who participate in screening using the hemoccult test, the...

To diagnose colorectal cancer, the hemoccult test is conducted to detect occult blood in the stool. For symptom-free people over 50 years old who participate in screening using the hemoccult test, the following information is available.

The probability that one of these people has colorectal cancer is 0.3 percent. If a person has colorectal cancer, the probability is 50 percent that he will have a positive hemoccult test. If a person does not have colorectal cancer, the probability is 3 percent that he will still have a positive hemoccult test. Imagine a person (over age 50, no symptoms) who has a positive hemoccult test in your screening. What is the probability that this person actually has colorectal cancer?”