In the dataset "infectionrisk.txt", we are interested in the effect of average length of stay in the hospital (Stay) and number of X-rays (Xray) on the infection risk (InfctRsk). 1. Fit a multiple linear regression model based on the three variables and report the regression equation. 2. Calculate the VIFs. Is there any multicollinearity? 3. Add a quadratic term of the predictor variable Stay in the above model. Report the new quadratic regression equation. 4. Calculate the VIFs w.r.t the new quadratic model. 5. Should we keep the quadratic term? Why? Data file https://drive.google.com/file/d/14E-AteAiXccFtXrmlp8M_sTD5BqRM8Z9/view?usp=drivesdk