$1.-$ Using the information in the table, prepare an aggregate production plan using a constant level strategy. Demand forecasts are shown below:

Year $-$ Forecast

$1300$

$2120$

$3200$

$4110$

$5135$

There is an initial inventory of $20$ products in the first year, it is known that the production capacity per year per worker is $20$ products.

$1.$ How many workers are needed for an aggregate production plan for the $5$ years that satisfies demand?

$2.$ What is the ending inventory for each year?