Refer to Exercise 15.1. The study was conducted and the yields in pounds of blueberries over a growing season are given in the following table.

a. Use residual plots to determine if there appear to be a violations in the conditions of normality and equal variance of the residuals.
b. What is the standard error in estimating the mean yield for each of the five methods of irrigation?
c. What is the standard error in estimating the difference in the mean yields of two of the methods of irrigation?
d. Is there significant evidence at the α = .05 level that the five methods of irrigation ­differ in their mean yields?
e. Use a multiple- comparison procedure to determine which pairs of the five meth­ods of ­irrigation have different means.

Method of Irigation Farm Surfuce Trickle Center Poin Luter Subirrigation Fann Mean 597 248 636 382 591 348 366 649 258 512 321 423 406 400 608 380 391 434 492 468 457 406 466 502 559 469 464.3 423 461 504 580 449 464 550 526 469 550 4976 350 370 460 452 343 340 327 378 419 458 389.6 401.9 456.6 478.9 493.9 430.9 408.7 470.8 500.0 507.3 493.2 464.2 588 689 690 10 Method Mean 616.3 353.2