The regression model y = x T + v predicts the life span (age at death) of a person in some population, where the feature vector x encodes various attributes of the person. Assuming the model fits actual life span data reasonably well (although of course not very accurately for any particular individual) what would you guess about 3, if x3 = 1 means the person is a smoker, and x3 = 0 means the person is not a smoker? For example, do you think that 3 is positive? Negative? Feel free to guess a plausible value for 3.