Reight car loadings over an 18-week period at a busy port are as follows: week number week number week number 1 250 7 295 13 410 2 260 8 325 14 415 3 270 9 355 15 435 4 260 10 345 16 445 5 270 11 375 17 455 6 275 12 405 18 465 a. determine a linear trend line for expected freight car loadings. (round your intermediate calculations and final answers to 2 decimal places.) yˆ = + t b. use the above trend equation to predict expected loadings for weeks 20 & 21. (round your final answers to 2 decimal places.) the forecasted demand for week 20 is and for week 21 is . c. the manager intends to install new equipment when the volume exceeds 830 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.) it should reach 830 loadings in week