\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$y$[/tex] \\
\hline
0 & 0 \\
\hline
1 & 1 \\
\hline
4 & 4 \\
\hline
5 & 5 \\
\hline
\end{tabular}

What is the correlation coefficient for the data shown in the table?

A. 0
B. 1
C. 4
D. 5



Answer :

To find the correlation coefficient for the given data points [tex]\((x, y)\)[/tex] in the table, we follow these steps:

[tex]\[ \begin{array}{|c|c|} \hline x & y \\ \hline 0 & 0 \\ \hline 1 & 1 \\ \hline 4 & 4 \\ \hline 5 & 5 \\ \hline \end{array} \][/tex]

Step-by-Step Solution:

1. Calculate the means of [tex]\(x\)[/tex] and [tex]\(y\)[/tex]:
[tex]\[ \bar{x} = \frac{0 + 1 + 4 + 5}{4} = \frac{10}{4} = 2.5 \][/tex]
[tex]\[ \bar{y} = \frac{0 + 1 + 4 + 5}{4} = \frac{10}{4} = 2.5 \][/tex]

2. Calculate the variance and the standard deviations of [tex]\(x\)[/tex] and [tex]\(y\)[/tex]:

Variance of [tex]\(x\)[/tex]:
[tex]\[ \sigma_x^2 = \frac{(0 - 2.5)^2 + (1 - 2.5)^2 + (4 - 2.5)^2 + (5 - 2.5)^2}{4} = \frac{6.25 + 2.25 + 2.25 + 6.25}{4} = 4.25 \][/tex]
Standard deviation of [tex]\(x\)[/tex]:
[tex]\[ \sigma_x = \sqrt{4.25} \][/tex]

Variance of [tex]\(y\)[/tex]:
[tex]\[ \sigma_y^2 = \frac{(0 - 2.5)^2 + (1 - 2.5)^2 + (4 - 2.5)^2 + (5 - 2.5)^2}{4} = \frac{6.25 + 2.25 + 2.25 + 6.25}{4} = 4.25 \][/tex]
Standard deviation of [tex]\(y\)[/tex]:
[tex]\[ \sigma_y = \sqrt{4.25} \][/tex]

3. Calculate the covariance of [tex]\(x\)[/tex] and [tex]\(y\)[/tex]:
[tex]\[ \text{Cov}(x, y) = \frac{(0 - 2.5)(0 - 2.5) + (1 - 2.5)(1 - 2.5) + (4 - 2.5)(4 - 2.5) + (5 - 2.5)(5 - 2.5)}{4} \][/tex]
[tex]\[ = \frac{(6.25) + (2.25) + (2.25) + (6.25)}{4} = 4.25 \][/tex]

4. Calculate the correlation coefficient [tex]\(r\)[/tex]:
[tex]\[ r = \frac{\text{Cov}(x, y)}{\sigma_x \sigma_y} \][/tex]
[tex]\[ r = \frac{4.25}{\sqrt{4.25} \cdot \sqrt{4.25}} = \frac{4.25}{4.25} = 1 \][/tex]

However, we recognize that extremely high precision results might exhibit minor deviations due to computational differences. In this case, the very precise result given is:

[tex]\[ r \approx 0.9999999999999998 \][/tex]

Thus, the correlation coefficient for the data is approximately:

[tex]\[ r \approx 0.9999999999999998 \][/tex]

This suggests a near-perfect positive linear relationship between the variables [tex]\(x\)[/tex] and [tex]\(y\)[/tex].