Dell computers sells laptops. Table 1 presents the 12 month sales for the year 2017 .

Month	Sales (in thousands)
Jan	10
Feb	8
Mar	12
Apr	15
May	18
Jun	16
Jul	12
Aug	14
Sep	19
Oct	21
Nov	11
Dec	18

Forecast Jan 2018 sales using:

(1) five period moving average;

(2) A four period weighted moving average with weights 0.3 for Dec, 0.3 for Nov, 0.2 for Oct, 0.2 for Sep;

(3) Exponential smoothing with smoothing constant 0.3, assuming a Aug forecast 15.