Question

Select the correct answer.

Answer 1

Answer:

A. 0.099

Step-by-step explanation:

Conditional Probability

We use the conditional probability formula to solve this question. It is

$P(B|A) = \frac{P(A \cap B)}{P(A)}$

In which

P(B|A) is the probability of event B happening, given that A happened.

$P(A \cap B)$ is the probability of both A and B happening.

P(A) is the probability of A happening.

In this question:

Event A: She does not have a heart attack.

Event B: tests predicts that she will have a heart attack

The doctors told her that the reliability of the stress test is 67%.

This means that there is a 100 - 67 = 33% of not having a heart attack if the test predicts she will have a heart attack, so:

$P(B|A) = 0.33$

70% risk of heart attack

So 100 - 70 = 30% probability of not having a heart attack, which means that $P(A) = 0.3$

What is the probability that Erin will not have a heart attack and the test predicts that she will?

$P(B|A) = \frac{P(A \cap B)}{P(A)}$

$P(A \cap B) = P(B|A)*P(A) = 0.33*0.3 = 0.099$

The correct answer is given by option A.