The following data represent y = the number of passenger cars retired from service and x = the number of new passenger cars registered during the years 1991-1995.
a. Determine the least-squares regression line and interpret its slope.
b. Estimate, for a year in which million new passenger cars are registered, the number of cars that will be retired from service.
c. Estimate, for a year in which 9.0 million new passenger cars are registered, the number of cars that will be retired from service.