(c) Use a calculator to verify that [tex]\Sigma x=24.0, \Sigma x^2=85.48, \Sigma y=53.5, \Sigma y^2=457.33[/tex] and [tex]\Sigma xy=190.02[/tex].

Compute [tex]r[/tex]. (Round your answer to four decimal places.)

[tex]r \stackrel{i}{=}\ \square[/tex]



Answer :

Let's compute the correlation coefficient [tex]\( r \)[/tex] using the given data. The correlation coefficient formula is:

[tex]\[ r = \frac{n\Sigma xy - (\Sigma x)(\Sigma y)}{\sqrt{[n \Sigma x^2 - (\Sigma x)^2][n \Sigma y^2 - (\Sigma y)^2]}} \][/tex]

Given values:
[tex]\[ \Sigma x = 24.0 \][/tex]
[tex]\[ \Sigma x^2 = 85.48 \][/tex]
[tex]\[ \Sigma y = 53.5 \][/tex]
[tex]\[ \Sigma y^2 = 457.33 \][/tex]
[tex]\[ \Sigma xy = 190.02 \][/tex]
[tex]\[ n = 5 \][/tex]

### Step-by-Step Calculation

1. Calculate the numerator:
[tex]\[ \text{{numerator}} = n \Sigma xy - (\Sigma x)(\Sigma y) \][/tex]
[tex]\[ \text{{numerator}} = 5 \cdot 190.02 - (24.0 \cdot 53.5) \][/tex]
[tex]\[ \text{{numerator}} = 950.1 - 1284 \][/tex]
[tex]\[ \text{{numerator}} = -333.9 \][/tex]

2. Calculate the denominator:
[tex]\[ \text{{denominator}} = \sqrt{[n \Sigma x^2 - (\Sigma x)^2][n \Sigma y^2 - (\Sigma y)^2]} \][/tex]

- First, compute [tex]\( n \Sigma x^2 - (\Sigma x)^2 \)[/tex]:
[tex]\[ n \Sigma x^2 - (\Sigma x)^2 = 5 \cdot 85.48 - (24.0)^2 \][/tex]
[tex]\[ = 427.4 - 576 \][/tex]
[tex]\[ = -148.6 \][/tex]

- Next, compute [tex]\( n \Sigma y^2 - (\Sigma y)^2 \)[/tex]:
[tex]\[ n \Sigma y^2 - (\Sigma y)^2 = 5 \cdot 457.33 - (53.5)^2 \][/tex]
[tex]\[ = 2286.65 - 2862.25 \][/tex]
[tex]\[ = -575.6 \][/tex]

- Now, compute the product:
[tex]\[ [n \Sigma x^2 - (\Sigma x)^2][n \Sigma y^2 - (\Sigma y)^2] = (-148.6) \times (-575.6) \][/tex]
[tex]\[ = 85560.16 \][/tex]

- Finally, take the square root:
[tex]\[ \text{{denominator}} = \sqrt{85560.16} \][/tex]
[tex]\[ = 292.4622 \][/tex]

3. Compute [tex]\( r \)[/tex]:
[tex]\[ r = \frac{\text{{numerator}}}{\text{{denominator}}} \][/tex]
[tex]\[ r = \frac{-333.9}{292.4622} \][/tex]
[tex]\[ r \approx -1.1417 \][/tex]

Therefore, the correlation coefficient [tex]\( r \)[/tex] rounded to four decimal places is:

[tex]\[ r \approx -1.1417 \][/tex]