A Time Series with Forecast Values Is Presented in the Following

Multiple Choice

A time series with forecast values is presented in the following table: $$\begin{array} { | r | r | r | } \hline \text { Month } & \text { Actual. } & \text { Forecast } \\\hline J a n & a & \\\hline \text { Mar } & 12 a & 1.1 a \\\hline \text { May} & 1.15 a & 1.2 a \\\hline J ul & 1.25 a & 12.21 a \\\hline \mathrm { Sep } & 1.3 a & 1.25 a \\\hline\end{array}$$
If the mean absolute deviation (MAD) is 257, then a = ______.

A) 4283.33
B) 428.33
C) 15.42
D) 42.833
E) 1.542