Create a Confidence Interval for the Slope of a Regression $= 7.67 - 3.30$

Create a confidence interval for the slope of a regression equation.
-As the carbon content in steel increases, its ductility tends to decrease. A researcher at
A steel company measures carbon content and ductility for a sample of 15 types of steel.
Based on these data he obtained the following regression results. The regression equation is
Ductility $= 7.67 - 3.30$ Carbon Content

$\begin{array} { l r r r r } \text { Predictor } & \text { Coef } & \text { SE Coef } & \text { T } & \text { P } \\ \text { Constant } & 7.671 & 1.507 & 5.09 & 0.000 \\ \text { Carbon Content } & - 3.296 & 1.097 & - 3.01 & 0.010 \end{array}$
$$S = 2.36317 \quad \mathrm { R } - \mathrm { Sq } = 41.0 \% \quad \mathrm { R } - \mathrm { Sq } ( \mathrm { adj } ) = 36.5 \%$$
The 95% confidence interval for the slope of the regression equation is

A) -5.456 to -1.136
B) -4.393 to -2.199
C) 6.164 to 9.178
D) -5.666 to -0.926
E) 2.581 to 12.761