a. For each of the 4 explanatory variables police, unemp, register, and weekly, choose an appropriate method to determine if any of these variables individually has an effect on homicide rate that is significant at the .05 level. Of the 4 explanatory variables police, unemp, register, and weekly, which variable explains the greatest proportion of the observed variation among the values of homicide rate? Why would you make this conclusion? b. Display the relationship between police force size and homicide rate using an appropriate graphical method. c. Calculate the estimated homicide rate for a police force of 250 officers per 100,000 population and do the same for a police force of 350 officers per 100,000 population. Which police force had the higher estimated homicide rate? d. Create the best model using a multivariate method by including and excluding variables for the best fit. Each variable contained in the final model should explain a significant amount of the observed variability in homicide rate. What do you conclude