A study of fox rabies in southern Germany gave the following information about different regions and the occurrence of rabies in each region. A random sample of n1 = 16 locations in region 1 gave the following information about the number of cases of fox rabies near that location. x1:   Region I Data 2 7 7 7 7 8 8 1 3 3 3 2 5 1 4 6 A second random sample of n2 = 15 locations in region II gave the following information about the number of cases of fox rabies near that location. x2:   Region II Data 1 3 4 3 3 8 5 4 4 4 2 2 5 6 9 (a) Does this information indicate that there is a difference (either way) in the mean number of cases of fox rabies between the two regions? Use a 5% level of significance. (Assume the distribution of rabies cases in both regions is mound-shaped and approximately normal.) (i) What is the level of significance?State the null and alternate hypotheses. H0: μ1 ≠ μ2; H1: μ1 = μ2H0: μ1 = μ2; H1: μ1 ≠ μ2      H0: μ1 > μ2; H1: μ1 = μ2   H0: μ1 = μ2; H1: μ1 > μ2   H0: μ1 = μ2; H1: μ1 < μ2 (ii) What sampling distribution will you use? What assumptions are you making? The Student's t. We assume that both population distributions are approximately normal with known standard deviations.   The standard normal. We assume that both population distributions are approximately normal with known standard deviations.   The Student's t. We assume that both population distributions are approximately normal with unknown standard deviations.   The standard normal. We assume that both population distributions are approximately normal with unknown standard deviations. What is the value of the sample test statistic? (Test the difference μ1 − μ2. Round your answer to three decimal places.)(iii) Find the P-value. (Round your answer to four decimal places.)Sketch the sampling distribution and show the area corresponding to the P-value.         (iv) Based on your answers in parts (i) to (iii), will you reject or fail to reject the null hypothesis? Are the data statistically significant at level α? Since the P-value ≤ α, we reject H0. The data are statistically significant.   Since the P-value ≤ α, we fail to reject H0. The data are statistically significant.   Since the P-value > α, we reject H0. The data are not statistically significant.   Since the P-value > α, we fail to reject H0. The data are not statistically significant. (v) Interpret your conclusion in the context of the application.   Reject H0. At the 5% level of significance, the evidence is sufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions.   Fail to reject H0. At the 5% level of significance, the evidence is insufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions.   Fail to reject H0. At the 5% level of significance, the evidence is sufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions.   Reject H0. At the 5% level of significance, the evidence is insufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions. (b) Find a 95% confidence interval for μ1 − μ2. (Round your answers to two decimal places.) lower limit        upper limit        Explain the meaning of the confidence interval in the context of the problem. At the 95% level of confidence, we can conclude that the number of cases of fox rabies differs between the two regions.   At the 95% level of confidence, we cannot conclude that the number of cases of fox rabies differs between the two regions.

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A study of fox rabies in southern Germany gave the following information about different regions and the occurrence of rabies in each region. A random sample of n1 = 16 locations in region 1 gave the following information about the number of cases of fox rabies near that location.

x1:   Region I Data
2 7 7 7 7 8 8 1
3 3 3 2 5 1 4 6

A second random sample of n2 = 15 locations in region II gave the following information about the number of cases of fox rabies near that location.

x2:   Region II Data
1 3 4 3 3 8 5 4
4 4 2 2 5 6 9


(a) Does this information indicate that there is a difference (either way) in the mean number of cases of fox rabies between the two regions? Use a 5% level of significance. (Assume the distribution of rabies cases in both regions is mound-shaped and approximately normal.)

(i) What is the level of significance?


State the null and alternate hypotheses.

H
0: μ1 ≠ μ2; H1: μ1 = μ2H0: μ1 = μ2; H1: μ1 ≠ μ2   
 
H0: μ1 > μ2; H1: μ1 = μ2
 
H0: μ1 = μ2; H1: μ1 > μ2
 
H0: μ1 = μ2; H1: μ1 < μ2

(ii) What sampling distribution will you use? What assumptions are you making?

The Student's t. We assume that both population distributions are approximately normal with known standard deviations.
 
The standard normal. We assume that both population distributions are approximately normal with known standard deviations.
 
The Student's t. We assume that both population distributions are approximately normal with unknown standard deviations.
 
The standard normal. We assume that both population distributions are approximately normal with unknown standard deviations.

What is the value of the sample test statistic? (Test the difference μ1 − μ2. Round your answer to three decimal places.)


(iii) Find the P-value. (Round your answer to four decimal places.)


Sketch the sampling distribution and show the area corresponding to the P-value.
   
   

(iv) Based on your answers in parts (i) to (iii), will you reject or fail to reject the null hypothesis? Are the data statistically significant at level α?
Since the P-value ≤ α, we reject H0. The data are statistically significant.
 
Since the P-value ≤ α, we fail to reject H0. The data are statistically significant.
 
Since the P-value > α, we reject H0. The data are not statistically significant.
 
Since the P-value > α, we fail to reject H0. The data are not statistically significant.

(v) Interpret your conclusion in the context of the application.
 
Reject H0. At the 5% level of significance, the evidence is sufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions.
 
Fail to reject H0. At the 5% level of significance, the evidence is insufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions.
 
Fail to reject H0. At the 5% level of significance, the evidence is sufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions.
 
Reject H0. At the 5% level of significance, the evidence is insufficient to indicate that there is a difference in the mean number of cases of fox rabies between the two regions.

(b) Find a 95% confidence interval for μ1 − μ2. (Round your answers to two decimal places.)

lower limit       
upper limit       


Explain the meaning of the confidence interval in the context of the problem.

At the 95% level of confidence, we can conclude that the number of cases of fox rabies differs between the two regions.
 
At the 95% level of confidence, we cannot conclude that the number of cases of fox rabies differs between the two regions.    
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