Augment the data by the dummy variable "cooling tower" as given in Table 6.

1. Build a multiple regression model to predict ln (C) by taking S and N or their natural logarithms, as well as CT, as the independent variables. Make sure to check for multicollinearity.
2. Use residual analysis and R² to check your model.
3. State which variables are important in predicting the cost of constructing an LWR plant.
4. State a prediction equation that can be used to predict ln(C).
5. Does adding CT improve R²? If so, by what amount?

Table 5:

Plant CT O 2 3 4 5 6 7 O 8 O 9 O 10 11 O 12 O 13 14 O 15 O 16 O 17 O 18 19 O 20 O 2122 O 23 24 O 25 26 27 O 28 O 29 30 31 O 32