#model-conditions

Question 1: Select all that apply

Which statements about a multiple regression model fitted to observational data are true? Select all that apply.

If two observations differ only in $x_1$ , by one unit, and $b_1 = 2.5$ , the predictions differ by 2.5.1
If two predictors are collinear, removing one of them leaves the other's coefficient estimate unchanged.2
If $b_1 = 5.7$ , raising an observation's $x_1$ by one unit would raise its $y$ by 5.7.3
With 472 observations, mildly skewed residuals without extreme outliers make the model unusable.4