Got these answers and they were wrong Exercises 15.12 through 15.16 are based on

ID: 432787 • Letter: G

Question

Got these answers and they were wrong

Exercises 15.12 through 15.16 are based on the following situation: International Machinery, Inc., produces a tractor and wishes to use quarterly tractor sales data observed in the last four years to predict quarterly tractor sales next year. The following MegaStat output gives the tractor sales data and the estimates of the seasonal factors and trend line for the data: ? Int Mach Centered Sales, y CMA Indexes Deseasonalized Moving Ratio to Seasonal t Year uarter Sales Average 293 392 221 147 388 512 287 184 479 640 347 223 581 755 410 266 1.191 1.521 0.804 0.484 1.191 1.521 0.804 0.484 1.191 1.521 0.804 0.484 1.191 1.521 0.804 0.484 245.9 257.7 275.0 303.9 500 325.7 400 336.6 357.1 380.4 402.0 420.7 431.8 461.0 487.7 496.3 510.2 549.9 700y19.95x + 220.54 R2 0.9965 275.125 02.000 325.250 338.125 354.125 381.500 405.000 417.375 435.000 462.125 484.375 497.625 0.803 0.487 1.193 1.514 0.810 0.482 1.183 1.533 0.798 0.483 1.199 1.517 4 300 200 100 4 10 12 Quarter 12 Sales, y Deseasonalized Linear (Deseasonalized) 15 16 4 4 4

Explanation / Answer

The FIrst prediction of all four quarters for 5th year.

The Point Prediction = sn x tr

tr = 19.95t + 220.54

sn x tr

1.191

559.69

666.59

1.521

579.64

881.63

0.804

599.59

482.07

0.484

619.54

299.86

(B) the 95% COnfidence interval 17 = P17 +- half - length confidence interval length = 666.59 +- 14 * 1.191 = 666.59 +- 16.674 = (649.92, 683.26)

The 95% COnfidence interval 18 = P18 +- half - length confidence interval length = 881.63 +- 1.521 * 14.4 = 881.63 +- 21.90 = (859.73, 903.53)

The 95% COnfidence interval 19 = P19 +- half - length confidence interval length = 482.07 +- 0.804 * 14.6 = 482.07 +- 11.74 = (470.33, 493.81)

The 95% COnfidence interval 20 = P20 +- half - length confidence interval length = 299.86 +- 0.484 * 15 = (292.6, 307.12)