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A survey was taken of children between the ages of 3 and 7. Let [tex]$A$[/tex] be the event that the person has 2 siblings, and let [tex]$B$[/tex] be the event that the person does not have a pet.

\begin{tabular}{|c|c|c|c|c|c|}
\hline
& \begin{tabular}{c} 0 \\ Siblings \end{tabular} & \begin{tabular}{c} 1 \\ Sibling \end{tabular} & \begin{tabular}{c} 2 \\ Siblings \end{tabular} & \begin{tabular}{c} 3 or \\ More \\ Siblings \end{tabular} & Total \\
\hline
Has a Pet & 29 & 84 & 27 & 10 & 150 \\
\hline
\begin{tabular}{c} Does Not \\ Have a Pet \end{tabular} & 31 & 45 & 18 & 6 & 100 \\
\hline
Total & 60 & 129 & 45 & 16 & 250 \\
\hline
\end{tabular}

Which statement is true about whether [tex]$A$[/tex] and [tex]$B$[/tex] are independent events?

A. [tex]$A$[/tex] and [tex]$B$[/tex] are independent events because [tex]$P(A \mid B) = P(A) = 0.18$[/tex].

B. [tex]$A$[/tex] and [tex]$B$[/tex] are independent events because [tex]$P(A \mid B) = P(A) = 0.4$[/tex].

C. [tex]$A$[/tex] and [tex]$B$[/tex] are not independent events because [tex]$P(A \mid B) = 0.4$[/tex] and [tex]$P(A) = 0.18$[/tex].

D. [tex]$A$[/tex] and [tex]$B$[/tex] are not independent events because [tex]$P(A \mid B) = 0.18$[/tex] and [tex]$P(A) = 0.4$[/tex].


Sagot :

Given the provided survey data, our task is to determine whether the events [tex]\( A \)[/tex] (the person has 2 siblings) and [tex]\( B \)[/tex] (the person does not have a pet) are independent events or not.

To do this, we need to calculate the following probabilities:

1. [tex]\( P(A) \)[/tex]: The probability that the person has 2 siblings.
2. [tex]\( P(B) \)[/tex]: The probability that the person does not have a pet.
3. [tex]\( P(A \mid B) \)[/tex]: The probability that the person has 2 siblings given that the person does not have a pet.

For [tex]\( A \)[/tex] and [tex]\( B \)[/tex] to be independent events, [tex]\( P(A \mid B) \)[/tex] should be equal to [tex]\( P(A) \)[/tex].

Step-by-Step Calculation:

1. Calculate [tex]\( P(A) \)[/tex]:
[tex]\[ P(A) = \frac{\text{Total number of people with 2 siblings}}{\text{Total number of survey participants}} = \frac{45}{250} = 0.18 \][/tex]

2. Calculate [tex]\( P(B) \)[/tex]:
[tex]\[ P(B) = \frac{\text{Total number of people who do not have a pet}}{\text{Total number of survey participants}} = \frac{100}{250} = 0.4 \][/tex]

3. Calculate [tex]\( P(A \mid B) \)[/tex]:
[tex]\[ P(A \mid B) = \frac{\text{Number of people with 2 siblings and no pet}}{\text{Total number of people who do not have a pet}} = \frac{18}{100} = 0.18 \][/tex]

4. Compare [tex]\( P(A \mid B) \)[/tex] and [tex]\( P(A) \)[/tex]:
[tex]\[ P(A \mid B) = 0.18 \quad \text{and} \quad P(A) = 0.18 \][/tex]

Since [tex]\( P(A \mid B) = P(A) = 0.18 \)[/tex], we can conclude that the events [tex]\( A \)[/tex] and [tex]\( B \)[/tex] are independent.

Therefore, the correct statement is:

A and B are independent events because [tex]\( P(A \mid B) = P(A) = 0.18 \)[/tex].
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