A study of the US clinical population found that 24.3% are diagnosed with a mental disorder, 13.4% are diagnosed with an alcohol-related disorder, and 4% are diagnosed with both disorders. (a) What is the probability that someone from the clinical population is diagnosed with a mental disorder, knowing that the person is diagnosed with an alcohol-related disorder? Please use 3 decimal places. .275 Incorrect: Your answer is incorrect. (b) What is the probability that someone from the clinical population is diagnosed with an alcohol-related disorder, knowing that the person is diagnosed with a mental disorder? Please use 3 decimal places.

Respuesta :

Answer:

a) 0.299

b) 0.165

Step-by-step explanation:

A probability is the number of desired outcomes divided by the number of total outcomes.

We solve this problem building the Venn's diagram of these probabilities.

I am going to say that:

A is the probability that a person from the clinical population is diagnosed with mental disorder.

B is the probability that a person from the clinical population is diagnosed with alcohol related disorder.

We have that:

[tex]A = a + (A \cap B)[/tex]

In which a is the probability that a person is diagnosed with mental disorder but not alcohol related disorder and [tex]A \cap B[/tex] is the probability that a person is diagnosed with both of these disorders.

By the same logic, we have that:

[tex]B = b + (A \cap B)[/tex]

We find the values of a,b and the intersection, starting from the intersection.

4% are diagnosed with both disorders.

This means that [tex]A \cap B = 0.04[/tex]

13.4% are diagnosed with an alcohol-related disorder

This means that [tex]B = 0.134[/tex]

So

[tex]B = b + (A \cap B)[/tex]

[tex]0.134 = b + 0.04[/tex]

[tex]b = 0.094[/tex]

24.3% are diagnosed with a mental disorder

This means that [tex]A = 0.243[/tex]

So

[tex]A = a + (A \cap B)[/tex]

[tex]0.243 = a + 0.04[/tex]

[tex]a = 0.203[/tex]

(a) What is the probability that someone from the clinical population is diagnosed with a mental disorder, knowing that the person is diagnosed with an alcohol-related disorder?

Desired outcomes:

Mental and alcohol-related disorders. So [tex]A \cap B[/tex]. So [tex]D = 0.04[/tex]

Total outcomes:

Alcohol-related disorder, which is [tex]B[/tex]. So [tex]T = 0.134[/tex]

Probability:

[tex]P = \frac{0.04}{0.134} = 0.299[/tex]

(b) What is the probability that someone from the clinical population is diagnosed with an alcohol-related disorder, knowing that the person is diagnosed with a mental disorder?

Desired outcomes:

Mental and alcohol-related disorders. So [tex]A \cap B[/tex]. So [tex]D = 0.04[/tex]

Total outcomes:

Mental health disorder, which is [tex]A[/tex]. So [tex]T = 0.243[/tex]

Probability

[tex]P = \frac{0.04}{0.243} = 0.165[/tex]