AP Grading Every Year Educational Testing Services (ETS) Selects Graders

Essay

AP Grading Every year Educational Testing Services (ETS) selects graders for the
Advanced Placement (AP) Exams. Recently the AP Statistics exam has been graded in
Lincoln, Nebraska. One objective of ETS is to have consistent grading by inviting graders
from all over the nation. However travel expenses are an issue. The accountants at ETS
wonder if the flight costs from cities west of Lincoln are the same as flight costs from cities
east of Lincoln. A random sample of the expense vouchers from last year was reviewed for
the cost of airline tickets. The data are shown in the table below. Indicate what inference
procedure you would use to see if there is a significant difference in the costs of airline
flights to Lincoln from the west and from the east, then decide if it is okay to actually
perform that inference procedure.
(Check the appropriate assumptions and conditions and indicate whether you could or
could not proceed. You do not have to do the actual test.) $$\begin{array} { | c | c | } \hline \text { Cost from east } & \text { Costs from west } \\\hline 265 & 257 \\\hline 298 & 320 \\\hline 340 & 295 \\\hline 219 & 288 \\\hline 199 & 366 \\\hline 398 & 275 \\\hline 359 & 430 \\\hline 309 & 397 \\\hline 105 & 253 \\\hline 253 & 366 \\\hline\end{array}$$