please work it without using excel

Demand for stereo headphones and music 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 this year was as follows:

MONTH	DEMAND (UNITS)
January	4,220
February	4,320
March	4,020
April	4,420
May	5,020
June	4,720
July	5,320
August	4,920
September	5,420
October	5,720
November	6,320
December	6,020

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 3.8. (Do not round intermediate calculations. Round your answers to 2 decimal places.) 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.)

Month January February March April May June July August September October November December Forecast Least Squares Regression Analysis (1) (2) (3) t y txy 1 2 600 1,550 1,500 1,500 2,400 3,100 2,600 2,900 3,800 10 4,500 11 4,000 12 4,900 78 33,350 t = 6.5 b=359.6154 y = 2,779.17 a = 441.6667 Therefore, Y = 441.67 + 359.6t St=363.9 3 4 5 7 8 9 600 3,100 4,500 6,000 12,000 18,600 18,200 23,200 34,200 45,000 44,000 58,800 268,200 (4) f 1 4 9 16 25 36 49 64 81 100 121 144 650 (5) y 360,000 2,402,500 2,250,000 2,250,000 5,760,000 9,610,000 6,760,000 8,410,000 14,440,000 20,250,000 16,000,000 24,010,000 112,502,500 (6) Y 801.3 1,160.9 1,520.5 1,880.1 2,239.7 2,599.4 2,959.0 3,318.6 3,678.2 4,037.8 4,397.4 4,757.1