5. What is the MAPE using the exponential smoothing (ES) method (using a= 0.15)? 6. What is the forecast for Week 8 using the exponential smoothing (using a= 0.15 ) forecasting method (Assume the forecast for the first week is 137)? 7. Which of these methods is the best forecasting method? Choose one error measurement for comparison. Explain using quantitative values. \begin{tabular}{|c|c|} \hline Month & Sales \\ \hline 1 & 137 \\ \hline 2 & 136 \\ \hline 3 & 147 \\ \hline 4 & 136 \\ \hline 5 & 141 \\ \hline 6 & 128 \\ \hline 7 & 132 \\ \hline \end{tabular}