Thread: Please Help No Idea!!

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)


PLEASE HELP!!!

Originally Posted by jobear

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)


PLEASE HELP!!!

You need to get Pr(oil|+ve).

A tree diagram is the easiest approach to take.

Start with the oil:

/oil (0.01)
\no oil (0.99)

and then add the +ve test and -ve test branches for each.

You should get as the answer:



Alternatively, you can chew on what the good Captain has said at your double post.