The following table reports the percentage of stocks in a portfolio for nine quarters from 2007 to 2009.

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                Quarter               Stock%
               1st—2007             29.8
               2nd—2007            31.0
               3rd—2007             29.9
               4th—2007             30.1
               1st—2008             32.2
               2nd—2008            31.5
               3rd—2008             32.0
               4th—2008             31.9
               1st—2009             30.0

  a. Construct a time series plot. What type of pattern exists in the data?
  b. Use trial and error to find a value of the exponential smoothing coefficient ɑ that results in a relatively small MSE.
  c. Using the exponential smoothing model you developed in part (b), what is the forecast of the percentage of stocks in a typical portfolio for the second quarter of 2009?