University officials hope that changes they have made have improved the retention rate. Last year, a sample of 2049 freshmen showed that 1537 returned as sophomores. This year, 1516 of 1942 freshmen sampled returned as sophomores. Determine if there is sufficient evidence at the 0.05 level to say that the retention rate has improved. Let last year's freshmen be Population 1 and let this year's freshmen be Population 2.   Step 2 of 3 :   Compute the value of the test statistic. Round your answer to two decimal places.

A software company is interested in improving customer satisfaction rate from the 60% currently claimed. The company sponsored a survey of 148 customers and found that 95 customers were satisfied. What is the test statistic z?

A father is concerned that his teenage son is watching too much television each day, since his son watches an average of 2 hours per day His son says that his TV habits are no different than those of his friends. Since this father has taken a stats class, he knows that can actually test to see whether or not his son is watching more TV than his peers The father collects a random sample of watching times from boys at his son's high school and gets the following data: 1.9, 2.3, 2.2, 1.9, 1.6, 2.6, 1.4, 2.0, 2.0, 2.2 Find a 95% confidence interval for the true mean number of hours teenagers at that school watch TV. a. Confidence Interval b. Conclusion

A new vaccination is being used in a laboratory experiment to investigate whether it is effective. There are 279 subjects in the study. Is there sufficient evidence to determine if vaccination and disease status are related? Vaccination Status Diseased Not Diseased 54 71 125 Vaccinated Not Vaccinated Total 33 121 154 Total 87 192 279 Copy Data Step 6 of 8: Find the critical value of the test at the 0.025 level of significance. Round your answer to three decimal places.

A random sample of size 21 was taken from a normal population. The sample average was 9.87 and the sample SD was 1.17. At the significance level of 10%, what test should you use for testing whether the population mean equals 9.7? One sample z-test for the population mean. two sample z-test for the population means. One sample z-test for proportions. two sample z-test for proportions. one sample t-test for the population mean. 3 26

An auditor for a local court system is tasked with comparing the rulings of two judges. The auditor needs to determine if Judge Hughes issues shorter sentences than Judge Wilson. The data below are the sentence lengths, in months, issued by each judge in their last twelve cases that dealt with operating a motor vehicle without a license. Test the claim that Judge Hughes issues shorter sentences than Judge Wilson for this particular type of case at the 0.05 level of significance. Let Judge Hughes' sentences be Population 1 and let Judge Wilson's sentences be Population 2. Assume that both populations are approximately normal and that the population variances are equal. Judge 24 12 12 30 36 30 12 18 24 12 24 30 Hughes Judge Wilson 36 36 24 24 24 24 18 12 30 24 18 30 Step 3 of 3: Draw a conclusion and interpret the decision. Copy Data

A software company is interested in improving customer satisfaction rate from the 65% currently claimed. The company sponsored a survey of 248 customers and found that 170 customers were satisfied. What is the test statistic z?

A publisher reports that 69 % of their readers own a particular make of car. A marketing executive wants to test the claim that the percentage is actually under the reported percentage. A random sample of 200 found that 60% of the readers owned a particular make of car. Is there sufficient evidence at the 0.10 level to support the executive's claim? Step 5 of 7: Identify the value of the level of significance.

Clothes dried outside smell better than those dried in a dryer because of a process called photolysis. Sunlight breaks down compounds that cause odor. A trained smeller is asked to smell a random sample of 20 towels. The smeller does not know it, but all of the 20 towels have been dried in the sun. The smeller is blindfolded and is not allowed to touch the towels but leans forward to smell the towel then rates the towel on a smell-scale of 1 to 10, where 1 is the an extremely unpleasant smell and 10 is a very good smell. A smell rating of 8 is typically attributed to a towel that is dried in the dryer. The mean smell rating for these 20 towels is approximately normal with a mean of 8.45 and the standard deviation is 0.887. A statistician performs a test of Ho μ = 8 versus H₁ μ> 8 where is the true mean smell rating for all towels dried in the sun. This test yields a P-value of 0.0176. What conclusion would you make at the significance level a = 0.05? Because the P-value of 0.0176 < α =…

A statistician changes her level of significance from .001 to .05.  What impact will this change have on her risk of making a Type I and Type II error?  Is the change in the level of significance a good decision?  Why or why not?