(This is a classical example of time series analysis in hydrology.) The Wabash river water level, Wt (meter), is measured once every month. The following AR-type model has been suggested:   Where   is...

(This is a classical example of time series analysis in hydrology.) The Wabash river water level, Wt (meter), is measured once every month. The following AR-type model has been suggested:

Where
  is a white noise process with variance 4. What is the expected water level according to this model? What is the standard deviation?