Freight car loadings over an 18-week period at a busy port are as follows: Week Number Week Number Week Number 1 400 7 465 13 575 2 415 8 495 14 580 3 430 9 525 15 610 4 415 10 510 16 625 5 430 11 540 17 640 6 435 12 570 18 655 Click here for the Excel Data File a. Determine a linear trend line for expected freight car loadings. (Round your intermediate calculations and final answers to 2 decimal places.)