Twenty weeks of data on the Commodity Futures Index are as follows. 7.36 7.40 7.56 7.56 7.59 7.52 7.51 7.70 7.61 7.55 7.52 7.68 7.84 7.72 7.86 7.73 7.77 7.86 7.82 7.64 (a) Construct a time series plot. What type of pattern exists in the data? The data appear to follow a trend and seasonal pattern. The data appear to follow an upward trend pattern. The data appear to follow a downward trend pattern. The data appear to follow a seasonal pattern. The data appear to follow a cyclical pattern. (b) Use trial and error to find a value of the exponential smoothing coefficient a that results in a relatively small MSE. Consider smoothing constants of a = 0.2, 0.4, and 0.6. (Round your answers to four decimal places.) MSE 0.2 0.4 0.6 The value of a that yields the smallest MSE is a = 0.6