4. Consider the following time series data for daily sales of a product over the past 3 weeks: Day Weck 1 Week 2 Week 3 Mon 200 400 550 Tuc 300 500 750 Wed 420 620 850 Thu 630 810 950 Fri 500 700 800 Sat 400 600 700 Sun 300 500 600 a. (5 pts.) Use Excel to construct a time series plot. Provide the line chart in file. your Excel b. (10 pts.) Introduce necessary variables to account for trend and seasonality in the data above and build an appropriate regression model (You are not required to specify the values of coefficients). c. (10 pts.) Specify the complete regression model in the box below. Provide your Excel file. d. (5 pts.) Make a forecast for Monday in week 4