Please explain and show all work

Calculate the Mean Square Error (MSE) for the 3, 4, and 6 month values. MSE=average((actual-forecast)^2)

Forecast the upcoming periods sales using the moving average series with the lowest MAD

Why is it inadvisable to use the Moving Average approach to forecast much further into the future?

Month	Sale	Month	Sale	Month	Sale
Oct-12	13.30	Oct-13	24.01	Oct-14	50.56
Nov-12	1.70	Nov-13	32.67	Nov-14	60.06
Dec-12	11.44	Dec-13	23.19	Dec-14	61.73
Jan-13	15.52	Jan-14	34.85	Jan-15	54.14
Feb-13	13.76	Feb-14	33.22	Feb-15	59.26
Mar-13	19.71	Mar-14	35.67	Mar-15	41.49
Apr-13	12.19	Apr-14	33.45	Apr-15	56.34
May-13	12.21	May-14	27.61	May-15	53.42
Jun-13	2.03	Jun-14	22.90	Jun-15	44.94
Jul-13	15.02	Jul-14	35.72	Jul-15	57.71
Aug-13	12.79	Aug-14	28.65	Aug-15	54.78
Sep-13	13.48	Sep-14	37.13	Sep-15	68.25