Are Amazon River dolphins endangered?

To solve the problem using the critical region method of testing, we need to first calculate the differences between the percentages of CEO salary increase and corporate revenue increase: d = B - A d = (22 - 18), (6 - 18), (28 - 19), (18 - 14), (6 + 4), (4 - 19), (21 - 15), (37 - 30) d = 4, -12, 9, 4, 10, -15, 6, 7 Next, we calculate the sample mean and sample standard deviation of d: Mean (d) = ?d / n = (4 - 12 + 9 + 4 + 10 - 15 + 6 + 7) / 8 = 3/8 = 0.375 s = ?[?(d - Mean(d))^2 / (n - 1)] = ?[152.125 / 7] = 2.403 Using a 5% level of significance, we need to find the critical value for a two-tailed test with 7 degrees of freedom. We can find this value by looking up the t-distribution table or using a calculator. The critical value is \approx imately ± 2.365. The test statistic for the difference in population mean percentage increases is: t = Mean(d) / (s / ?n) = 0.375 / (2.403 / ?8) = 0.782 Since our test statistic of 0.782 is less than the critical value of ±2.365, we fail to reject the null hypothesis. This means that there is insufficient evidence to claim a difference in population mean percentage increases for corporate revenue and CEO salary. Comparing our conclusion with the conclusion obtained by using the P-value method, we find that they are the same. The P-value for our test is \approx imately 0.454, which is greater than 0.05 (our level of significance). Therefore, we fail to reject the null hypothesis using the P-value method as well.