A crime has been committed in a town of 100,000 inhabitants. The police are looking for a single perpetrator, believed to live i
n town. DNA evidence is found on the crime scene. Kevin’s DNA matches the DNA recovered from the crime scene. According to DNA experts, the probability that a random persons DNA matches the crime scene DNA is 1 in 10,000. Before the DNA evidence, Kevin was no more likely to be the guilty person than any other person in town. What is the probability that Kevin is guilty after the DNA evidence appeared?
Because the probability that the DNA of a random person matches the DNA of the crime scene is 1/10000, that is 0.01%, then the probability that Kevin is guilty after the test is 9999/10000, that is, 99.99%.
