saint '''''' a. Construct a time-series graph of the sales data for HeathCo's line of skiwear (see data in c5p11 ). Does there appear to be a seasonal pattern in the sales data? Explain why you think the results are as you have found. (c5p11 ) b. It seems logical that skiwear would sell better from October through March than from April through September. To test this hypothesis, begin by adding two dummy variables to the data: a dummy variable 01 = 1 for each first quarter (January, February, March) and Q1 = 0 othenrvise; and a dummy variable Q4 = 1 for each fourth quarter (October, November, December) and Q4 = 0 otherwise. Once the dummy variables have been entered into your data set, estimate the following trend model: SALES bo + b1 (TIME) + bZQ1 + b3Q4 Evaluate these results by answering the following: Do the signs make sense? Why or why not? - Are the coefficients statistically different from zero at a 95 percent confidence level (one-tailed test)? . What percentage of the variation in SALES is explained by this model