A department manager using a combination of methods has forecast sales of toasters at a local department store as follows.

Month Unit Sales Manager's Forecast

May $66$

June $51$

July $4750$

August $4455$

September $3052$

October $5542$

November $7460$

December $12575$

What is this forecasting technique's approximate MSE?

Question $3$ options:

$41$

$580$

$3479$

$2500$