Problem 3-7 (Static) Freight car loadings over an 18-week period at a busy port are as follows: Week Number Week Number Week Number 1 220 7 350 13 460 2 245 8 360 14 475 3 280 9 400 15 4 275 10 380 ook 16 56 500 510 5 300 11 420 17 525 6 310 12 450 18 rint 541 rences Click here for the Excel Data File a. Determine a linear trend line for expected freight car loadings. (Round your intermediate calculations decimal places.) = b. Use the trend equation to predict expected loadings for weeks 20 and 21. (Round your final answers to The forecasted demand for week 20 and 21 is and respectively