Drew is a demand analyst at the Ruby Memorial Hospital and has collected data for a commonly used surgical instrument. However, Drew$$s dog ate the work, and Drew needs to do some quick calculations to fill in some details for a presentation to Dr$.$ Paine $($the boss$)$ in the next ten minutes $($Assume one period ahead forecasts$).$

Demand

Year Month Demand

$2019$ Sept $319$

$2019$ Oct $295$

$2019$ Nov $305$

$2019$ Dec $287$

$2020$ Jan $300$

$2020$ Feb $295$

$2020$ Mar $290$

$2020$ Apr $285$

$2020$ May $280$

$2020$ Jun $293$

$2020$ Jul $305$

$2020$ Aug $327$

Calculate a weighted moving average forecast $($N$=3)$ for December $2019.$ Drew recalled the first two weights were $0\mathrm{.}5$ and $0\mathrm{.}4$ but can$$t remember the third weight.