I HAVE NO IDEA ON THIS ONE IM SO LOST
A geologist is using seismographs to test for oil. It is found that if oil is present, the test gives a positive result 95% of the time, and if oil is not present, the test gives a positive result 2% of the time. Oil is actually present in 1% of the cases tested. If the test shows positive, what is the probability that oil is present??????
(solved in either a tree diagram, contingency table or proper formula and substitution)