Suppose that for the general population , 1 in 5000 people carries the human imm

Question

Suppose that for the general population , 1 in 5000 people carries the human immunodeficiency virus (HIV) . A test
for the presence of HIV yields either a positive (+) or negative (-) response . Suppose the test gives the correct
answer 99% of the time.What is P[ -|H], the condition probability that a person test negative given the person does
have the HIV virus ? What is P[ H | +], the conditional probability that a randomly chosen person has the HIV virus
given that the person tests positive ?

Explanation / Answer

A. In part A we already know that the person has the HIV virus. So the probability that said person will test Negative is .01 or 1 percent because it has a 99% detection rate. a) .01 or 1% B. In part be it is noted that we are choosing a random person. We know that 1 in 5000 have the HIV virus. So the probability of picking a person with HIV is 1/5000 or .0002 percent. And the probability of this person with HIV testing positive for HIV is 99% so our answer is b) .0002*.99 = .000198

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.