3. (12pis) The quarterly sales for specific educational software over the past five years are given in the following a) Compute the four seasonal factors by using the data or the past nve years. b) Forecast the yearly sales for Year 6 using a 3-year moving. Forecast the quarterly demand for Year 6 12pts) A manager would like to estimate the proportion of his employees' time spent performing arious gardening and lawn care activities including mowing, trimming, raking and miscellaneous. he manager estimates that mowing should spend around 15% of the total, and the manager wants a 5% confidence that the resulting estimate will be within 5% of the true value. hat sample size should the manager use