Answered

Alejandro surveyed his classmates to determine who has ever gone surfing and who has ever gone snowboarding. Let [tex]$A$[/tex] be the event that the person has gone surfing, and let [tex]$B$[/tex] be the event that the person has gone snowboarding.

[tex]\[
\begin{tabular}{|c|c|c|c|}
\hline & \begin{tabular}{c}
Has \\
Snowboarded
\end{tabular} & \begin{tabular}{c}
Never \\
Snowboarded
\end{tabular} & Total \\
\hline Has Surfed & 36 & 189 & 225 \\
\hline Never Surfed & 12 & 63 & 75 \\
\hline Total & 48 & 252 & 300 \\
\hline
\end{tabular}
\][/tex]

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]$P(A \mid B) = P(A) = 0.16$[/tex].

B. [tex]$A$[/tex] and [tex]$B$[/tex] are independent events because [tex]$P(A \mid B) = P(A) = 0.75$[/tex].

C. [tex]$A$[/tex] and [tex]$B$[/tex] are not independent events because [tex]$P(A \mid B) = 0.16$[/tex] and [tex]$P(A) = 0.75$[/tex].

D. [tex]$A$[/tex] and [tex]$B$[/tex] are not independent events because [tex]$P(A \mid B) = 0.75$[/tex] and [tex]$P(A) = 0.16$[/tex].



Answer :

To determine whether the events [tex]\( A \)[/tex] (a student has gone surfing) and [tex]\( B \)[/tex] (a student has gone snowboarding) are independent, we'll check if [tex]\( P(A \mid B) = P(A) \)[/tex].

Given data:

- Total number of students surveyed: [tex]\( 300 \)[/tex]
- Students who have gone surfing ([tex]\( A \)[/tex]): [tex]\( 225 \)[/tex]
- Students who have gone snowboarding ([tex]\( B \)[/tex]): [tex]\( 48 \)[/tex]
- Students who have gone both surfing and snowboarding ([tex]\( A \cap B \)[/tex]): [tex]\( 36 \)[/tex]

First, we'll calculate the probabilities:

1. Probability that a student has gone surfing [tex]\( P(A) \)[/tex]:
[tex]\[ P(A) = \frac{\text{Number of students who have gone surfing}}{\text{Total number of students}} = \frac{225}{300} \][/tex]

2. Probability that a student has gone snowboarding [tex]\( P(B) \)[/tex]:
[tex]\[ P(B) = \frac{\text{Number of students who have gone snowboarding}}{\text{Total number of students}} = \frac{48}{300} \][/tex]

3. Probability that a student has gone surfing given that they have gone snowboarding [tex]\( P(A \mid B) \)[/tex]:
[tex]\[ P(A \mid B) = \frac{\text{Number of students who have gone both surfing and snowboarding}}{\text{Number of students who have gone snowboarding}} = \frac{36}{48} \][/tex]

Now, substituting the values:

1. Calculating [tex]\( P(A) \)[/tex]:
[tex]\[ P(A) = \frac{225}{300} = 0.75 \][/tex]

2. Calculating [tex]\( P(B) \)[/tex] (though not directly needed):
[tex]\[ P(B) = \frac{48}{300} \][/tex]

3. Calculating [tex]\( P(A \mid B) \)[/tex]:
[tex]\[ P(A \mid B) = \frac{36}{48} = 0.75 \][/tex]

Since [tex]\( P(A \mid B) = P(A) = 0.75 \)[/tex], the events [tex]\( A \)[/tex] and [tex]\( B \)[/tex] are indeed independent.

Thus, the correct statement is:
[tex]\( A \)[/tex] and [tex]\( B \)[/tex] are independent events because [tex]\( P(A \mid B) = P(A) = 0.75 \)[/tex].

So, the correct answer is:
[tex]\( A \)[/tex] and [tex]\( B \)[/tex] are independent events because [tex]\( P(A \mid B) = P(A) = 0.75 \)[/tex].