Freight car loadings over an 18 -week period at a busy port are as follows: 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.) b. Use the above trend equation to predict expected loadings for Weeks 20 \& 21. (Round your final answers to 2 decimal places.) c. The manager intends to install new equipment when the volume exceeds 820 loadings per week. Assuming the current trend continues, in which week (at the earliest) should the loading volume reach that level? (Use the rounded answers, as required, from any previous part of this problem. Do not round any other intermediate calculations. Round your final answer to 2 decimal places.)