Awater well is being drilled in the desert where soil is either rock, clay, or sand. probability of rock p(r) = 0.42, probability of clay p(c) = 0.34, and probability of sand p(s) =0.24. a geological test gives positive results with 40% accuracy in rock, 50% accuracy with clay, and 80% accuracy in sand. given the test is positive, what is the probability that the soil is rock, p(rock|positive)? use bayes’ rule.