Ethylene glycol and propylene glycol are liquids used in antifreeze and deicing solutions. Ethylene glycol is listed as a hazardous chemical by the Environmental Protection Agency, while propylene glycol is generally regarded as safe. Table 11 lists the freezing temperature for various concentrations (as a percentage of total weight) of each chemical in a solution used to deice airplanes. A linear regression model for the ethylene glycol data in Table 11 is

E = -0.55T + 31
where E is the percentage of ethylene glycol in the deicing solution and T is the temperature at which the solution freezes.

(A) Draw a scatter plot of the data and a graph of the model on the same axes.
(B) Use the model to estimate the freezing temperature to the nearest degree of a solution that is 30% ethylene glycol.
(C) Use the model to estimate the percentage of ethylene glycol in a solution that freezes at 15°F.

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Table 11 Freezing Temperatures Freezing Temperature ('F) Ethylene Glycol (% Wt.) Propylene Glycol (% Wt.) -50 56 58 -40 53 55 -30 49 52 -20 45 48 -10 40 43 33 36 10 25 29 20 16 19