MONTH DEMAND (UNITS) January 4, 115 February 4, 215 March 3,915 April 4, 315 May 4, 915 June 4, 615 July 5, 215 August 4, 815 September 5, 315 October 5, 615 November 6, 215 December 5, 915 a. Using linear regression analysis, what would you estimate demand to be for each month next year? Using a spreadsheet, follow the general format in Exhibit 3.7. Note: Do not round intermediate calculations. Round your answers to 2 decimal places. Month Forecast January February March April May June July August September October November Decemberb. To be reasonably confident of meeting demand, Nina decides to use 4 standard errors of estimate for safety. How many additional units should be held to meet this level of confidence? Note: Do not round intermediate calculations. Round your answer to the nearest whole number. Additional units h22