12.9 Cell phone specs Refer to the cell phone data set available on the book’s website, which shows various specs of a random sample of cell phones. Engineers would like to analyze how the weight (measured in grams) of a phone depends on the size of the battery, the heaviest component of a cell phone. Here, the size is measured by the capacity of the battery, which is the amount of energy it can supply on a full charge (measured in milliampere-hours, mAh).

a. Identify the response and explanatory variables and then construct and interpret the scatterplot. Mention any outliers you see.

b. What effect will the outlier have on the fitted regression equation? Will its residual be positive or negative, and will it be small or large in absolute value?

c. Remove the outlier and find the prediction equation.

Predict the weight of a cell phone when the battery capacity is (i) 1,000 mAh and (ii) 1,500 mAh.

d. Interpret the slope in context.