As the Carbon Content in Steel Increases, Its Ductility Tends $= 7.67 - 3.30$

Multiple Choice

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, which of the
Following statements is NOT true? The regression equation is
Ductility $= 7.67 - 3.30$ Carbon Content
$\begin{array} { l r r r r } \text { Predictor } & \text { Coef } & \text { SE Coef } & \text { T } & \text { P } \\ \text { Constant } & 7.671 & 1.507 & 5.09 & 0.000 \\ \text { Carbon Content } & - 3.296 & 1.097 & - 3.01 & 0.010 \end{array}$
$$\mathrm { S } = 2.36317 \quad \mathrm { R } - \mathrm { Sq } = 41.0 \% \quad \mathrm { R } - \mathrm { Sq } ( \mathrm { adj } ) = 36.5 \%$$

A) The association between carbon content and ductility of steel is statistically
Significant at α = 0.05.
B) The slope is significantly different from zero at α = 0.05.
C) The relationship between carbon content and ductility of steel is positive at α =0.05.
D) There is 59% of the variance in ductility that is not explained by this model.
E) For one unit increase in carbon content, one can expect a 3.30 unit decrease in
Ductility.