\begin{tabular}{|c|c|c|c|c|}
\hline & [tex]$X$[/tex] & [tex]$Y$[/tex] & [tex]$Z$[/tex] & Total \\
\hline A & 45 & 30 & 60 & 135 \\
\hline B & 20 & 10 & 25 & 55 \\
\hline C & 25 & 35 & 50 & 110 \\
\hline Total & 90 & 75 & 135 & 300 \\
\hline
\end{tabular}

Which statement is true about whether C and Y are independent events?

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

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

C. [tex]$C$[/tex] and [tex]$Y$[/tex] are not independent events because [tex]$P(C \mid Y) \neq P(Y)$[/tex].

D. [tex]$C$[/tex] and [tex]$Y$[/tex] are not independent events because [tex]$P(C \mid Y) \neq P(C)$[/tex].



Answer :

To determine whether events [tex]\( C \)[/tex] and [tex]\( Y \)[/tex] are independent, we need to compare the conditional probability [tex]\( P(C \mid Y) \)[/tex] with the probability [tex]\( P(C) \)[/tex]. Two events are independent if and only if [tex]\( P(C \mid Y) = P(C) \)[/tex].

Let's break down the calculations step by step:

1. Total number of outcomes:
[tex]\[ \text{Total outcomes} = 300 \][/tex]

2. Total outcomes where [tex]\( C \)[/tex] occurs:
[tex]\[ \text{Total } C = 110 \][/tex]

3. Total outcomes where [tex]\( Y \)[/tex] occurs:
[tex]\[ \text{Total } Y = 75 \][/tex]

4. Outcomes where both [tex]\( C \)[/tex] and [tex]\( Y \)[/tex] occur:
[tex]\[ \text{C and Y} = 35 \][/tex]

5. Calculate [tex]\( P(C) \)[/tex]:
The probability of [tex]\( C \)[/tex] occurring is given by the ratio of outcomes where [tex]\( C \)[/tex] occurs to the total number of outcomes:
[tex]\[ P(C) = \frac{\text{Total } C}{\text{Total outcomes}} = \frac{110}{300} \approx 0.3667 \][/tex]

6. Calculate [tex]\( P(Y) \)[/tex]:
The probability of [tex]\( Y \)[/tex] occurring is given by the ratio of outcomes where [tex]\( Y \)[/tex] occurs to the total number of outcomes:
[tex]\[ P(Y) = \frac{\text{Total } Y}{\text{Total outcomes}} = \frac{75}{300} = 0.25 \][/tex]

7. Calculate [tex]\( P(C \text{ and } Y) \)[/tex]:
The probability of both [tex]\( C \)[/tex] and [tex]\( Y \)[/tex] occurring is given by the ratio of outcomes where both [tex]\( C \)[/tex] and [tex]\( Y \)[/tex] occur to the total number of outcomes:
[tex]\[ P(C \text{ and } Y) = \frac{\text{C and Y}}{\text{Total outcomes}} = \frac{35}{300} \approx 0.1167 \][/tex]

8. Calculate [tex]\( P(C \mid Y) \)[/tex]:
The conditional probability [tex]\( P(C \mid Y) \)[/tex] is given by the ratio of the probability of both [tex]\( C \)[/tex] and [tex]\( Y \)[/tex] occurring to the probability of [tex]\( Y \)[/tex] occurring:
[tex]\[ P(C \mid Y) = \frac{P(C \text{ and } Y)}{P(Y)} = \frac{0.1167}{0.25} \approx 0.4667 \][/tex]

9. Check for independence:
To determine if [tex]\( C \)[/tex] and [tex]\( Y \)[/tex] are independent, we compare [tex]\( P(C) \)[/tex] with [tex]\( P(C \mid Y) \)[/tex]. If [tex]\( P(C \mid Y) = P(C) \)[/tex], they are independent. Otherwise, they are not.

From our calculations:
[tex]\[ P(C) \approx 0.3667 \][/tex]
[tex]\[ P(C \mid Y) \approx 0.4667 \][/tex]

Since [tex]\( P(C \mid Y) \neq P(C) \)[/tex], we conclude:
[tex]\[ \text{C and Y are not independent events because } P(C \mid Y) \neq P(C). \][/tex]

Therefore, the correct statement is:

C and Y are not independent events because [tex]\( P(C \mid Y) \neq P(C) \)[/tex].