Problem 18-14 (Algo) Demand for stereo headphones and MP3 players for joggers has caused Nina Industries to grow almost 50 percent over the past year. The number of joggers continues to expand, so Nina expects demand for headsets to also expand, because, as yet, no safety laws have been passed to prevent joggers from wearing them. Demand for the players for last year was as follows: MONTH January February DEMAND (UNITS) 4,120 4,220 March 3,920 April 4,320 May 4,920 June 4,620 July 5,220 August 4,820 September 5,320 October 5,620 November 6,220 December 5,920 a. Using linear regression analysis, what would you estimate demand to be for each month next year? (Do not round intermediate calculations. Round your answers to 2 decimal places.) a. Using linear regression analysis, what would you estimate demand to be for each month next year? (Do not round intermediate calculations. Round your answers to 2 decimal places.) Month January February March April May June July August September October November December Forecast b. To be reasonably confident of meeting demand, Nina decides to use 3 standard errors of estimate for safety. How many additional units should be held to meet this level of confidence? (Do not round intermediate calculations. Round your answer to the nearest whole number.) Additional units