In a survey of a town, 56% of residents own a car, 21% of residents owns a truck, and 4% of residents own both a car and a truck. What is the conditional probability that a person who owns a car also owns a truck? A. 7% B. 17% C. 44% D. 19%

Respuesta :

Answer:

A. 7%

Step-by-step explanation:

We build the Venn's diagram of these probabilities.

I am going to say that:

A is the probability that a resident owns a car.

B is the probability that a resident owns a truck.

We have that:

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

In which a is the probability that a resident has a car but not a truck and [tex]A \cap B[/tex] is the probability that a resident has both a car and a truck.

By the same logic, we have that:

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

4% of residents own both a car and a truck.

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

56% of residents own a car

This means that [tex]A = 0.56[/tex]. So

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

[tex]0.56 = a + 0.04[/tex]

[tex]a = 0.52[/tex]

What is the conditional probability that a person who owns a car also owns a truck?

[tex]P(B|A) = \frac{A \cap B}{A} = \frac{0.04}{0.56} = 0.07[/tex]

So the correct answer is:

A. 7%