Exam 11: Inference on Two Samples

Construct a 95% confidence interval for - . Two samples are randomly selected from normal populations. The sample statistics are given below.

Find the test statistic to test the hypothesis that = . Two samples are randomly selected from each population. The sample statistics are given below. Use ? = 0.05.

Test the hypothesis that = . Use α = 0.05. The sample statistics listed below are from independent samples.Sample statistics: = 50, = 35, and = 60, = 40

Find the test statistic, t, to test the hypothesis that = . Two samples are randomly selected and come from populations that are normal. The sample statistics are given below.

Test the hypothesis that > . Use α = 0.01. The sample statistics listed below are from independent samples.Sample statistics: = 100, = 38, and = 140, = 50

A pharmaceutical company wishes to test a new drug with the expectation of lowering cholesterol levels. Ten subjects are randomly selected and pretested. The results are listed below. The subjects were placed on the drug for a period of 6 months, after which their cholesterol levels were tested again. The results are listed below. (All units are milligrams per deciliter.) Test the company's claim that the drug lowers cholesterol levels. Use α = 0.01. Assume that the distribution is normally distributed.

Construct a 95% confidence interval for - . Two samples are randomly selected from normal populations. The sample statistics are given below.

Seven randomly selected plants that bottle the same beverage implemented a time management program in hopes of improving productivity. The average time, in minutes, that it took the companies to produce the same quantity of bottles before and after the program are listed below. Assume the two population distributions are normal. Construct a 90% confidence interval for . Assume that the paired data came from a population that is normally distributed.

Test the hypothesis that ≠ . Two samples are randomly selected from each population. The sample statistics are given below. Use α = 0.02.

Construct a 95% confidence interval for - . Two samples are randomly selected from normal populations. The sample statistics are given below.

A physician claims that a person's diastolic blood pressure can be lowered if, instead of taking a drug, the person meditates each evening. Ten subjects are randomly selected and pretested. Their blood pressures, measured in millimeters of mercury, are listed below. The 10 patients are instructed in basic meditation and told to practice it each evening for one month. At the end of the month, their blood pressures are taken again. The data are listed below. Test the physician's claim. Use α = 0.01.

Perform the appropriate hypothesis test. -A random samples of 8 apples of variety A and an independent random sample of 13 apples of variety B yielded the following weights in ounces. Do the data provide sufficient evidence to conclude that the mean weight of apples of variety A differs from the mean weight of apples of variety B? Use the α = 0.10 level of significance. Assume that the sample data come from normally distributed populations with no outliers.

Test the hypothesis that = . Two samples are randomly selected from normal populations. The sample statistics are given below. Use α = 0.05.

Perform the appropriate hypothesis test. -A random sample of 100 male employees of a retail store results in a mean monthly salary of $ 720 with a standard deviation of $44. An independent random sample of 125 female employees of the same store results in a mean monthly salary of $ 705 with a standard deviation of $25. Does this constitute sufficient evidence to conclude that the mean monthly salary for male employees of the store is higher than the mean monthly salary for female employees of the store? Use the α = 0.01 level of significance.

Find the test statistic estimate, z, to test the hypothesis that > . Use ? = 0.01. The sample statistics listed below are from independent samples.Sample statistics: = 100, = 38, and = 140, = 50

A university wanted to see whether there was a significant difference in age between its day staff and evening staff. A random sample of 35 staff members is selected from each group. The data are given below. Test the hypothesis that there is no difference in age between the two groups. Use α = 0.05.

Test the hypothesis that > . Two samples are randomly selected from normal populations. The sample statistics are given below. Use α = 0.005.

A local company is concerned about the number of days missed by its employees due to illness. A random sample of 10 employees is selected. The number of days absent in one year is listed below. An incentive program is offered in an attempt to decrease the number of days absent. The number of days absent in one year after the incentive program is listed below. Test the claim that the incentive program cuts down on the number of days missed by employees. Use α = 0.05. Assume that the distribution is normally distributed.

Find the test statistic, t, to test the hypothesis that > . Two samples are randomly selected and come from populations that are normal. The sample statistics are given below.

Find the test statistic, t, to test the hypothesis that < . Two samples are randomly selected and come from populations that are normal. The sample statistics are given below.