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Assume that you have the revenue data of the last 4 months, but they are not ordered (You have only the numbers but you don't know which number matchs with which month). The revenues are 8.000 6, 9.000 , 11.000 & and 15.000 . You know that the revenue in September will be the forecast with weighted average method for the last 2 months (weights are 0,40 for July and 0,60 for August). And your total costs for September will be exactly 10.000 $. Assuming that the forecast with the weighted average method will be 100% accurate, what is the VaR in September with 90% confidence interval