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A set of data points has a line of best fit of [tex]y = -0.2x + 1.7[/tex]. What is the residual for the point [tex](5, 1)[/tex]?

A. 1.5
B. 0.3
C. 0.7
D. -0.3


Sagot :

To find the residual for the point [tex]\((5, 1)\)[/tex] given the line of best fit [tex]\( y = -0.2x + 1.7 \)[/tex], follow these steps:

1. Identify the coordinates of the point: The given point is [tex]\((5, 1)\)[/tex], where [tex]\( x = 5 \)[/tex] and [tex]\( y_{\text{observed}} = 1 \)[/tex].

2. Use the line of best fit equation to find the predicted [tex]\( y \)[/tex] value:
[tex]\[ y = -0.2x + 1.7 \][/tex]
Substituting [tex]\( x = 5 \)[/tex] into the equation:
[tex]\[ y_{\text{predicted}} = -0.2 \times 5 + 1.7 \][/tex]
Calculate the value:
[tex]\[ y_{\text{predicted}} = -1 + 1.7 = 0.7 \][/tex]

3. Calculate the residual: The residual is calculated as the difference between the observed [tex]\( y \)[/tex] value and the predicted [tex]\( y \)[/tex] value:
[tex]\[ \text{Residual} = y_{\text{observed}} - y_{\text{predicted}} \][/tex]
Substituting the values:
[tex]\[ \text{Residual} = 1 - 0.7 = 0.3 \][/tex]

Therefore, the residual for the point [tex]\((5, 1)\)[/tex] is [tex]\( 0.3 \)[/tex].

The correct answer is B. 0.3.