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A data set is shown in the table. The line of best fit modeling the data is [tex]$y = 2.69x - 7.95$[/tex].

\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$y$[/tex] \\
\hline
1 & -5.1 \\
\hline
2 & -3.2 \\
\hline
3 & 1.0 \\
\hline
4 & 2.3 \\
\hline
5 & 5.6 \\
\hline
\end{tabular}

What is the residual value when [tex]$x=3$[/tex]?

A. -0.88

B. -12

C. 0.12

D. 0.88


Sagot :

To determine the residual value when \(x = 3\) for the given data and the line of best fit \(y = 2.69x - 7.95\), we will follow these steps:

1. Calculate the predicted value \(\hat{y}\):
- Substitute \(x = 3\) into the equation of the line of best fit.
[tex]\[ \hat{y} = 2.69 \cdot 3 - 7.95 \][/tex]
- Perform the multiplication and subtraction:
[tex]\[ \hat{y} = 8.07 - 7.95 = 0.12 \][/tex]
Thus, the predicted value \(\hat{y}\) when \(x = 3\) is \(0.12\).

2. Find the actual observed value \(y\):
- From the table, when \(x = 3\), the actual observed value is \(y = 1.0\).

3. Calculate the residual:
- The residual \( \text{residual} = y - \hat{y} \).
- Substitute the actual value \( y = 1.0 \) and the predicted value \( \hat{y} = 0.12 \):
[tex]\[ \text{residual} = 1.0 - 0.12 = 0.88 \][/tex]

Therefore, the residual value when [tex]\(x = 3\)[/tex] is [tex]\(0.88\)[/tex].