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1.1) In many multiple regression data sets, the predictors X₁, X₂, ..., X_k are highly interdependent. When one of the X_is values can be predicted very well from the other predictor values, for at least one predictor, the data is said to exhibit __________.

1.2) The k^th -degree polynomial regression model equation is Y = 0 +1X +2X² +....+kX^k +, where is a normally distributed random variable with E () = ___________ and Var () = ___________.