Hello there,
I hope you and your family are staying safe and healthy during this winter season.

We need to use the Quadratic Formula*
, 
Thus, given the problem:

So now we just need to plug them in the Quadratic Formula*
, 
As you can see, it is a mess right now. Therefore, we need to simplify it
, 
Now that's get us to the final solution:
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It is my pleasure to help students like you! If you have additional questions, please let me know.
Take care!
~Garebear
Answer:
At a level of 95%, it is expected that the interval [0.45; 11.59] contains the value of the ductility in steel when its carbon content is 0.5%.
Step-by-step explanation:
Hello!
Considering the dependent variable:
Y: Ductility in steel.
And the independent variable:
X: Carbon content of the steel.
The linear regression was estimated and a prediction interval was calculated.
The prediction interval is calculated to predict a value that the variable Y (response variable) can take for a given value of the variable X (predictor variable) in the definition range of the linear regression line. Symbolically [Y/X=
]
In this case 95% prediction interval for Y/X=0.5
At a level of 95%, it is expected that the interval [0.45; 11.59] contains the value of the ductility in steel when its carbon content is 0.5%.
I hope it helps!
Her answer represents "-3.7 less than 4 times a number is 11.9". The correct equation should be -3.7n-4=-11.9.