The following table represents the demand for a specific type of cedar boards at Home Depot over the last $9$ months.

Month Demand $($in $1000$s$)$

January $23$

February $14$

March $19$

April $22$

May $17$

June $13$

July $21$

August $18$

September $12$

October $?$

Assuming

$,$

$,$ an initial forecast of $20$ for January, and an initial trend adjustment of $0$ for January, develop an exponential smoothing with trend adjustment forecast and clearly answer the following questions in your spreadsheet.

How many cedar boards are forecasted for October?

What is the MAPE $($Mean Absolute Percentage Error$)$ for the first nine months?