The breaking strength of 16 bundles of wool fibers have sample mean of 436 and sample standard deviation of 12. In addition, breaking strengths of 12 bundles of synthetic fibers have sample mean of 453 and sample standard deviation of 5.
a) Determine the mean strength of the wool bundles with a 95% condfidence interval.
b) Assuming constant variance, calculate the pooled sample variance.
c) Find the test statistic for the hypotheses H0 : u1 = u2 vs. H1 : u1 6=/u2.
d) Can we conclude that the mean strength for synthetic bundles is different from that of the wool bundles at 0.05 level of significance?