One international company is trying to optimize stocking and ordering for popular Apple mobiles, after looking back over the past $10$ months of sales, the company has determined the actual sales on the Apple mobiles and has placed the values in the table below, the average of the number of Apple mobiles sold during that period was, $35.$

$\backslash$table$[[$Months$,\backslash$table$[[$Sales$],[$forecast$]],$Actual sales$],[1,35,50],[2,-,25],[3,-,35],[4,-,20],[5,-,15],[6,-,10],[7,-,20],[8,-,20],[9,-,30],[10,-,35]]$