A taste test asks people from Texas and California which pasta they prefer, Brand A or Brand B. This table shows the results.

\begin{tabular}{|l|c|c|c|}
\hline & Brand A & Brand B & Total \\
\hline Texas & 80 & 45 & 125 \\
\hline California & 96 & 54 & 150 \\
\hline Total & 176 & 99 & 275 \\
\hline
\end{tabular}

A person is randomly selected from those tested. Are being from Texas and preferring Brand A independent events? Why or why not?

A. No, they are not independent because [tex]$P($Texas$) \approx 0.45$[/tex] and [tex][tex]$P($[/tex]Texas [tex]$\mid$[/tex] Brand A$) \approx 0.64$[/tex].

B. No, they are not independent because [tex][tex]$P($[/tex]Texas$) \approx 0.45$[/tex] and [tex][tex]$P($[/tex]Texas [tex]$\mid$[/tex] Brand A$) \approx 0.45$[/tex].

C. Yes, they are independent because [tex][tex]$P($[/tex]Texas$) \approx 0.45$[/tex] and [tex][tex]$P($[/tex]Texas [tex]$\mid$[/tex] Brand A$) \approx 0.45$[/tex].

D. Yes, they are independent because [tex][tex]$P($[/tex]Texas$) \approx 0.45$[/tex] and [tex][tex]$P($[/tex]Texas [tex]$\mid$[/tex] Brand A$) \approx 0.64$[/tex].



Answer :

To determine whether being from Texas and preferring brand A are independent events, we need to compare the probability of being from Texas [tex]\( P(\text{Texas}) \)[/tex] with the probability of being from Texas given that the person prefers brand A [tex]\( P(\text{Texas} \mid \text{Brand A}) \)[/tex].

1. Calculate [tex]\( P(\text{Texas}) \)[/tex]:

The total number of respondents is 275. Out of these, 125 are from Texas.

[tex]\[ P(\text{Texas}) = \frac{\text{Number of respondents from Texas}}{\text{Total number of respondents}} = \frac{125}{275} \approx 0.4545 \][/tex]

2. Calculate [tex]\( P(\text{Texas} \mid \text{Brand A}) \)[/tex]:

To find [tex]\( P(\text{Texas} \mid \text{Brand A}) \)[/tex], we look at the number of people who prefer brand A, which is 176, and out of those, the number of people from Texas who prefer brand A, which is 80.

[tex]\[ P(\text{Texas} \mid \text{Brand A}) = \frac{\text{Number of Texas respondents who prefer Brand A}}{\text{Total number of respondents who prefer Brand A}} = \frac{80}{176} \approx 0.4545 \][/tex]

3. Compare the probabilities:

[tex]\[ P(\text{Texas}) \approx 0.4545 \][/tex]
[tex]\[ P(\text{Texas} \mid \text{Brand A}) \approx 0.4545 \][/tex]

Since [tex]\( P(\text{Texas}) \approx P(\text{Texas} \mid \text{Brand A}) \)[/tex], being from Texas and preferring brand A are independent events. Therefore, the correct answer is:

C. Yes, they are independent because [tex]\( P(\text{Texas}) \approx 0.45 \)[/tex] and [tex]\( P(\text{Texas} \mid \text{Brand A}) \approx 0.45 \)[/tex].