Johnson Filtration, Inc., provides maintenance service for water filtration systems throughout southern Florida. Customers contact Johnson with requests for maintenance service on their water filtration systems. To estimate the service time and the service cost, Johnson's managers want to predict the repair time necessary for each maintenance request. Hence, repair time in hours is the dependent variable. Repair time is believed to be related to three factors; the number of months since the last maintenance service, the type of repair problem (mechanical or electrical), and the repairperson who performs the repair (Donna Newton or Bob Jones). Data for a sample of 10 service calls are reported in the following table. Repair Time in Hours Months Since Last Service 2.9 2 Electrical Donna Newton 3.0 6 Mechanical Donna Newton 4.8 8 Electrical Bob Jones 1.8 3 Mechanical Donna Newton 2.9 2 Electrical Donna Newton 4.9 7 Electrical Bob Jones 4.2 9 Mechanical Bob Jones 4.8 8 Mechanical Bob Jones 4.4 4 Electrical Bob Jones 4.5 6 Electrical Donna Newton Type of Repair Repairperson (a) Use the data to develop the simple linear regression equation to predict repair time given the number of months since the last maintenance service. Let x represent the number of months since the last maintenance service. If required, round your answers to four decimal places. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank. (Example: -300). = + x What is the coefficient of determination? If required, round your answers to four decimal places (b) Using the simple linear regression model developed in part (a), calculate the predicted repair time and residual for each of the ten repairs in the data. If required, round your answers to four decimal places. Repair Time in Hours Months Since Last Service 1.8 3 Mechanical Donna Newton 3.0 6 Mechanical Donna Newton 4.2 9 Mechanical Bob Jones 2.9 2 Electrical Donna Newton 2.9 2 Electrical Donna Newton 4.8 8 Electrical Bob Jones 4.8 8 Mechanical Bob Jones 4.5 6 Electrical Donna Newton 4.9 7 Electrical Bob Jones 4.4 4 Electrical Bob Jones Type of Repair Repairperso n Predicted Repair Time in Hours Residuals Create a scatter chart in Excel with months since last service on the x-axis and repair time in hours on the y-axis for which the points representing electrical and mechanical repairs are shown in different shapes and or colors. Choose the correct chart below. (i) (ii) (iii) (iv) - Select your answ er - Create a similar scatter chart in Excel of months since last service and repair time in hours for which the points representing Bob Jones and Donna Newton repairs are shown in different shapes and or colors. Choose the correct chart below. (i) (ii) (iii) (iv) - Select your answ er - (c) Create a new dummy variable that is equal to 0 if the type of repair is mechanical and 1 if the type of repair is electrical. Develop the multiple regression equation in Excel to predict repair time, given the number of months since the last maintenance service and the type of repair. Let x1 represent the number of months since the last maintenance service. Let x2 represent the type of repair. If required, round your answers to four decimal places. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank. (Example: -300). = + x1 + x2 .3876 What is the coefficient of determination? If required, round your answers to four decimal places. (d) Create a new dummy variable that is equal to 0 if the repairperson is Bob Jones and 1 if the repairperson is Donna Newton. Develop the multiple regression equation in Excel to predict repair time, given the number of months since the last maintenance service and the repairperson. Let x1 represent the number of months since the last maintenance service. Let x2 represent the repairperson. If required, round your answers to four decimal places. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank. (Example: -300) = + x1 + x2 What is the coefficient of determination? If required, round your answers to four decimal places. (e) Develop the multiple regression equation to predict repair time given the number of months since the last maintenance service, the type of repair, and the repairperson. Let x1 represent the number of months since the last maintenance service. Let x2 represent the type of repair. Let x3 represent the repairperson. If required, round your answers to four decimal places. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank. (Example: -300). = + x1 + x2 + What is the coefficient of determination? If required, round your answers to four decimal places. x3