a$.$ Because Ms$.$ Lynch has so many other job responsibilities, she has hired you to help with the forecasting effort. First, she would like you to prepare a time$-$series plot of the data and to write her memo indicating what the plot appears to show and whether it seems likely that a simple linear trend would be useful in preparing forecasts.

b$.$ In addition to plotting that data over time, you should estimate the least$-$squares trend line in the form:

SALES $=\_\_\_\_\_+/-\_\_\_\_\_\_($TIME$)$

c$.$ Do your regression results indicate to you that there is a s significant trend to the data? Explain why or why not.

d$.$ On the basis of your results, prepare a forecast for the four quarters of $2017.$

e$.$ A year later, Barbara gives you a call and tells you that the actual sales for the four quarters of $2017$b were: Q$1=334,271,$ Q$2=328,982,$ Q$3=317,921,$ and Q$4350,118.$ How accurate was your model? What was the mean absolute error?