010 (11.37) Mumbai Electronics is planning to extend its marketing region from the western United States to include the Midwestern states. In order to predict its sales in this new region the company has asked you to develop a linear regression of DVD system sales on price, using the following data supplied by the marketing department: Sales 418 J 384 343 407 ' 432 l 386 444 427 Price . 98 l 194 231 20'? . 89 l 255 149 195 a. Use an unbiased estimation procedure to nd an estimate of the variance of the error terms in the population regression. b. Use an unbiased estimation procedure to nd an estimate of the variance of the least squares estimator of the slope of the population regression line. c. Find a 90% condence interval for the slope of the population regression line