The breaking strengths of n = 20 bundles of wool fibers have a sample mean  = 436.5 and a sample standard deviation sx = 11.90. In addition, the breaking strengths of m = 25 bundles of synthetic fibers have a sample mean  = 452.8 and a sample standard deviation sy = 4.61. Answer the following questions without assuming that the two population variances are equal.
(a) Does a one-sided hypothesis test with size α = 0.01 accept or reject the null hypothesis that the synthetic fiber bundles have an average breaking strength no larger than the wool fiber bundles?
(b) What is a one-sided 99% confidence interval that provides an upper bound on μA - μB, where μA is the average breaking strength of wool fiber bundles and μB, is the average breaking strength of .synthetic-fiber bundles?
(c) Is there enough evidence to conclude that the average breaking strength of synthetic fiber bundles is larger than the average breaking strength of wool fiber bundles?
(This problem is continued in Problem 9.6.12.)