Two independent methods of forecasting based on judgment and experience have been prepared each month for the past $10$ months. The forecasts and actual sales are as follows:

Month Sales Forecast $1$ Forecast $2$

$1840835805$

$2840815815$

$3825830840$

$4855825830$

$5775790785$

$6840810796$

$7800785765$

$8845815840$

$9780825830$

$10840810825$

a$.$ Compute the MSE and MAD for each forecast. $($Round your answers to $2$ decimal places.$)$

b$.$ Compute MAPE for each forecast. $($Round your intermediate calculations to $5$ decimal places and final answers to $4$ decimal places.$)$

c$.$ Prepare a naive forecast for periods $2$ through $11$ using the given sales data. Compute each of the following; $(1)$ MSE, $(2)$ MAD, $(3)$ tracking signal at month $10,$ and $(4)2$s control limits$.($Negative values should be indicated by a minus sign. Round your answers to $2$ decimal places.$)$