Awater well is to be drilled in the desert where the soil is either rock, clay or sande. the probability of rock is p(r)=0.53. the clay probability is p(c)=0.21. the sand probability is p(s)=0.26. if it is rock, a geological test gives a positive result with 35% accuracy. if it is clay, a geological test gives a positive result with 48% accuracy. the test gives a positive result with 75% accuracy for sand. given the test is positive, what is the probability that soil is sand, p(sand l positive)?