30. The article Measuring and Understanding the Aging of Kraft Insulating Paper in Power Transformers

(IEEE Electr. Insul. Mag., 1996: 28—34) contained observations on degree of polymerization for paper specimens. There were observations for two different ranges of viscosity times concentration:

Middle range 418 421 421 422 425 427 431 434 437 439 446 447 448 453 454 463 465 Higher range 429 430 430 431 436 437 440 441 445 446 447

a. Construct a comparative boxplot for the two samples, and comment on any interesting features.

b. Calculate a 95% con dence interval for the difference between true average degree of polymerization for the middle range and that for the high range. Does the interval suggest that m1 and m2 may in fact be different? Explain your reasoning.