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Select the correct answer.

On discovering that her family had a 70% risk of heart attack, Erin took treadmill test to check her own potential of having a heart attack. The
doctors told her that the reliability of the stress test is 67%. What is the probability that Erin will not have a heart attack and the test predicts that
she will?
© A. 0.099
© B. 0.201
© C. 0.231
0.469

User Tmhs
by
4.1k points

1 Answer

4 votes

Answer:

A. 0.099

Explanation:

Conditional Probability

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


P(B|A) = (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) = (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.

User Schickb
by
4.5k points