Compositematerials used in themanufacture of aircraft Problem 11.3 componentsmust

be tested to determine tensile strength. A manufacturer tests five random

specimens from five randomly selected batches, obtaining the following coded

strengths (data from Vangel 1992).

Batch

1 379 357 390 376 376

2 363 367 382 381 359

3 401 402 407 402 396

4 402 387 392 395 394

5 415 405 396 390 395

Compute point estimates for the between batch and within batch variance

components, and compute a 95% confidence interval for 2

/2.