Answer:
Three-week moving average forecast


Explanation:
Given

Solving (a): Three-week moving average forecast
This is calculated as:

Since it is three-week, we start from t = 3
For t = 3; we consider months 1, 2 and 3


For t = 4; we consider months 2, 3 and 4


For t = 5; we consider months 3, 4 and 5


So, the forecast are:




Solving (b): MSE
To do this, we simply calculate the square of the forecast error
The forecast error (E) is:

So, we have:
Forecast error The square






