Consider two urns with the following composition: Urn 1 contains 5 red and 15 black balls, Urn 2 contains 8 red and 12 black balls. Our random experiment consists of choosing one of the two urns with equal probability and then drawing a sample (without replacement) of 3 balls. If 3 red balls are drawn, what is the probability they came from urn 1? How would the result change if the initial choice of the urn was as per the rule: Choose Urn 1 with probability 0.8 and Urn 2 with probability 0.2.