Problem $3.$ A company uses a tracking signal trigger of $\frac{+}{-}4$ to decide whether a forecast should be reviewed. Given the following history, determine in which period the forecast should be reviewed. MAD for the item is $15.$ Is there any previous indication that the forecast should be reviewed?

Understandable, you have to calculate the Deviation, Cumulative deviation and the tracking signal. $(4$ points$)$

$\backslash$table$[[$Period$,$Forecast,Actual,Deviation,$\backslash$table$[[$Cumulative$],[$deviation$]],\backslash$table$[[$Tracking$],[$signal$]]],[1,100,110,,,],[2,105,90,,,],[3,110,85,,,],[4,115,110,,,],[5,120,105,,,],[6,125,95,,,]]$