Listed below are costs (in dollars) of air fares for different airlines from New York City (JFK) to San Francisco. The costs are based on tickets purchased 30 days in advance and one day in advance, and the airlines are US Air, Continental, Delta, United, American, Alaska, and Northwest. Is there sufficient evidence to conclude that there is a linear correlation between costs of tickets purchased 30 days in advance and those purchased one day in advance?

Construct a scatterplot, find the value of the linear correlation coefficient r, and find the critical values of r from Table A-6 using ? = 0.05. Determine whether there is sufficient evidence to support a claim of a linear correlation between the two variables.?

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30 Days One Day 244 456 260 614 264 567 264 943 278 628 318 1088 280 536 TABLE A-6 Critical Values of the Pearson Correlation Coefficient r n TELEFONNING 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 25 30 35 40 45 50 60 70 80 90 100 α = .05 .950 .878 811 .754 .707 .666 .632 .602 576 .553 .532 .514 .497 482 468 .456 444 .396 .361 .335 312 294 279 254 236 220 207 .196 a = .01 .990 .959 .917 .875 .834 .798 .765 .735 .708 .684 .661 .641 .623 .606 .590 .575 .561 .505 .463 .430 .402 .378 .361 .330 .305 286 .269 .256