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 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, Do not round any other intermediate calculations. Round your final answer to 2 decimal places.)

Freight car loadings over 18 weeks 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