Question

Point estimate of H2 Pooled estimate Sp Remaining Time: 1 hour, 24 minutes, 41 seconds. Question Completion Status QUESTION 11 Look at the same problem given in Q.10. The following information pertains to a study of the effectiveness of a cleanup project on a lake. Prior to the project initiation, 12 water samples were obtained at randosm from this lake at the 2 pm peak period, and the amount of dissolved oxygen (in ppm) was recorded. The lake cleanup project was carried out, and 6 months after the cleanup, 12 water samples were again taken at the 2 pm peak period, independently of the first samples, and the amount of dissolved oxygen (in ppm) was again recorded Let ? 1 and al denote the mean and standard deviation of Population I (data after the cleanup), and let ?, and ?, denote the mean and standard deviation of Population 2 (data before the cleanup). Use the information from the detailed Mintab output shown below to answer this questi n. Use the 5% level of s gnif can e. , Choose one correct answer relating to checking whether the two population vanances ?1and ?2" are the same. Minitab Output Descriptive Statistics: Before, After VariableNNMean SE Mean St Dev Minimum 1 Median 3 Before 12 11.563 0.0989 0.343 11.000 11.262 11.550 11.875 12 10.775 0.113 0.391 10.200 10.450 10.750 11050 After Test and cI for Two Variances: Before, After Method Null hypothesis Alternative hypothesis Variance (Before) Variance (After) not-1 Significance level Variance (Before) Variance (After)1 Alpha - o.0s F method was used. This method is accurate for normal data only. Save All Answers Click Save and Submit to save and submit. Click Save All Answers to save all answers 0 Type here to search

Answer 1

For testing equality of two variances, we have the F-test.

The value of the test statistic is, 0.77.

We have the p=value of that test is 0.671 which is greater than 0.05. So, we don't reject the null hypothesis at 5% level of significance.

Now, from the obtained sample variance we can say that the side by side boxplot of the data from both samples shows approximately the same width.

So, the first option is correct.

We can't consider the second t-test because it's the test for checking equality of means.