Acrylamide is a chemical that is sometimes found in cooked starchy foods and which is thought to increase the risk of certain kinds of cancer. The paper “A Statistical Regression Model for the Estimation of Acrylamide Concentrations in French Fries for Excess Lifetime Cancer Risk Assessment” (Food and Chemical Toxicology [2012]: 3867–3876) describes a study to investigate the effect of x = Frying time (in seconds) and y = Acrylamide concentration (in micrograms per kilogram) in French fries. The data in the accompanying table are approximate values read from a graph that appeared in the paper.

Frying Time ........... Acrylamide Concentration
150 ............................................. 155
240 ............................................. 120
240 ............................................. 190
270 ............................................. 185
300 ............................................. 140
300 ............................................. 270

a. Construct a scatterplot of these data.

b. Find the equation of the least-squares line. Based on this line, what would you predict acrylamide concentration to be for a frying time of 270 seconds? What is the residual associated with the observation (270, 185)?