ASK YOUR TEACHER
In this problem, assume that the distribution of differences isapproximately normal. Note: For degrees of freedomd.f. not in the Student's t table, usethe closest d.f. that is smaller. Insome situations, this choice of d.f. may increasethe P-value by a small amount and therefore produce aslightly more \"conservative\" answer.
In environmental studies, sex ratios are of great importance. Wolfsociety, packs, and ecology have been studied extensively atdifferent locations in the U.S. and foreign countries. Sex ratiosfor eight study sites in northern Europe are shown below.
| Location of WolfPack | % Males(Winter) | % Males(Summer) |
| Finland | 62 | 65 |
| Finland | 64 | 69 |
| Finland | 74 | 47 |
| Lapland | 55 | 48 |
| Lapland | 64 | 55 |
| Russia | 50 | 50 |
| Russia | 41 | 50 |
| Russia | 55 | 45 |
It is hypothesized that in winter, \"loner\" males (not present insummer packs) join the pack to increase survival rate. Use a 5%level of significance to test the claim that the average percentageof males in a wolf pack is higher in winter. (Let d =winter − summer.)
What is the value of the sample test statistic? (Round your answerto three decimal places.)
In this problem, assume that the distribution of differences isapproximately normal. Note: For degrees of freedomd.f. not in the Student's t table, usethe closest d.f. that is smaller. Insome situations, this choice of d.f. may increasethe P-value by a small amount and therefore produce aslightly more \"conservative\" answer.
In the following data pairs, A represents birth rate andB represents death rate per 1000 resident population. Thedata are paired by counties in the Midwest. A random sample of 16counties gave the following information.
| A: | 12.7 | 13.4 | 12.6 | 12.3 | 11.4 | 11.1 | 14.2 | 15.1 |
| B: | 9.8 | 14.3 | 10.7 | 14.2 | 13.0 | 12.9 | 10.9 | 10.0 |
| A: | 12.5 | 12.3 | 13.1 | 15.8 | 10.3 | 12.7 | 11.1 | 15.7 |
| B: | 14.1 | 13.6 | 9.1 | 10.2 | 17.9 | 11.8 | 7.0 | 9.2 |
Do the data indicate a difference (either way) betweenpopulation average birth rate and death rate in this region? Useα = 0.01. (Let d = A − B.)
What is the value of the sample test statistic? (Round your answerto three decimal places.)
