00:01
For this problem, to begin, we have that the probability of having the disease, which i'll call p of d, is 10%, or 0 .1.
00:08
The probability of testing positive, given that the person has the disease.
00:14
So, probability of t, given d, is equal to 0 .95.
00:22
The probability of testing negative, given that the person does not have the disease.
00:28
So, t complement for a negative test, given d complement, not positive.
00:33
Having the disease is 0 .9.
00:38
For a, we're looking for the probability that a randomly chosen person tests positive.
00:44
So probability of a positive test.
00:46
We can find this using the law of total probability.
00:49
So that's going to be equal to p of t given d times p of d plus p of t given not d times p of d compliment or not d.
01:10
So let's see here.
01:13
Alright, so that's 0 .95 times 0 .1 plus 1 minus 0 .9, which would be 0 .1, times probability of not having the disease, which would be 1 minus 0 .1.
01:28
So we find that the total probability of testing positive is 0 .185...