a$-2.$ Forecast the preceding eight years, and determine the forecast errors. $($Negative answers should be indicated by a minus sign. Do not round intermediate calculations and round your final answer to $2$ decimal places.$)$ YearSales$(000)$ Forecast Error Error$2138\mathrm{.}60244\mathrm{.}70348\mathrm{.}10452\mathrm{.}50554\mathrm{.}90657\mathrm{.}60761\mathrm{.}60868\mathrm{.}00$ a$-3.$ Construct $2$s control limits$.($Round the final answer to $2$ decimal places.$)2$s control limits are $\backslash$pm b$.$ Using the model, forecast textbook sales for each of the next five years. $($Round the final answers to $1$ decimal place.$)$ Year Sales$(000)$ Forecast Error$974\mathrm{.}701076\mathrm{.}501183\mathrm{.}001286\mathrm{.}001390\mathrm{.}70$ c$.$ Suppose actual sales for the next five years turn out as follows: Year:$910111213$ Sales$(000)$:$74\mathrm{.}7076\mathrm{.}5083\mathrm{.}0086\mathrm{.}0090\mathrm{.}70$Calculate the forecast errors for years $9$ to $13.$ Is the forecasting process in control?