00:01
In this question, we're trying to find probability of finding oil.
00:03
And the question doesn't specify what quality of oil, just that we find oil.
00:08
So you can just look here at the probability that we don't find oil, that's 0 .3.
00:13
So the opposite of that, finding oil, is going to be 1 minus 0 .3.
00:18
So the probability of finding oil is 0 .7 or 70%.
00:23
And that makes sense, too, because you can see if we get high quality oil, that's 0 .5.
00:28
Medium quality is 0 .2.
00:30
Add those up together.
00:32
That gives you the probability of just finding oil, and that is 0 .7.
00:37
Now, part b, a soil test is taken after 200 feet of drilling of the first well, and the odds of finding soil is identified with a follow -up test.
00:48
So now we have new odds of finding oil, now that we've done the soil test...