From the table, we have the following points:
(x, y) ==> (1.6, 29), (1.6, 45), (1.75, 26), (1.95, 22), (2, 18), (2, 21), (2.3, 21), (2.5, 18)
Let's find the regression line.
Apply the slope-intercept form:
y = mx + b
Where m is the slope and b is the y-intercept.
To find the slope, apply the formula:
[tex]m=\frac{n(\Sigma xy)-\Sigma x\Sigma y}{n(\Sigma x^2)-(\Sigma x)^2}[/tex]Where:
• ∑x = 1.6 + 1.6 + 1.75 + 1.95 + 2 + 2 + 2.3 + 2.5 = 15.7
• ∑y = 29 + 45 + 26 + 22 + 18 + 21 + 21 + 18 = 200
• ∑xy = 1.6⋅29 + 1.6⋅45 + 1.75⋅26 + 1.95⋅22 + 2⋅18 +2⋅21 +2.3⋅21 + 2.5⋅18 = 378.1
• ∑x² = 1.6² + 1.6² + 1.75² + 1.95² + 2² + 2² + 2.3² + 2.5² = 31.525
,• n is the number of data = 8
Now, plug in values into the equation and solve for m:
[tex]\begin{gathered} m=\frac{8(378.1)-15.7*200}{8(31.525)-(15.7)^2} \\ \\ m=-20.175\approx20.2 \end{gathered}[/tex]The slope, m = -20.2
To find the y-intercept, b, apply the formula:
[tex]\begin{gathered} b=\frac{(\Sigma y)(\Sigma x^2)-\Sigma x\Sigma xy}{n(\Sigma x^2)-(\Sigma x)^2} \\ \\ b=\frac{200(31.525)-15.7*200}{8(31.525)-15.7^2} \\ \\ b=64.594\approx64.6 \end{gathered}[/tex]Therefore, the regression equation is:
y = 64.6 + (-20.2)x
(b). Substitute 1.8 for x in the equation and solve for y:
y = -20.2(1.8) + 64.6
y = 28.24 = 28.
ANSWER:
(A). y = 64.6 + (-20.2)x
(B). 28
