Exam 11: Two-Sample Tests of Hypothesis

A hypothesis tests that two population means are equal.A sample of 10 with a standard deviation of 5 is selected from the first population and a sample of 15 with a standard deviation of 5 from the second population.The standard deviations are equal.Testing the claim at the 0.01 level,what is the critical value? Assume unequal standard deviations.

A national manufacturer of ball bearings is experimenting with two different processes for producing precision ball bearings.It is important that the diameters be as close as possible to an industry standard.The output from each process is sampled and the average error from the industry standard is calculated.The results are presented below. The researcher is interested in determining whether there is evidence that the two processes yield different average errors.Assume that the population standard deviations are equal. What is the critical t value at the 1% level of significance?

Which of the following conditions must be met to conduct a test for the difference in two sample means?

For hypotheses that compare two population means,when is a pooled variance used?

20 randomly selected statistics students were given 15 multiple-choice questions and 15 open-ended questions - all on the same material.The professor was interested in determining which type of questions the students scored higher.This experiment is an example of

A committee studying employer-employee relations proposed that each employee would rate his or her immediate supervisor and in turn the supervisor would rate each employee.To find reactions regarding the proposal,120 office personnel and 160 plant personnel were selected at random.Seventy-eight of the office personnel and 90 of the plant personnel were in favor of the proposal.Computed z = 1.48.At the 0.05 level,it was concluded that there is sufficient evidence to support the belief that the proportion of office personnel in favor of the proposal is greater than that of the plant personnel.

For hypotheses that compare two population means,what test statistic if used when the population standard deviations are unknown?

A financial planner wants to compare the yield of income and growth mutual funds.Fifty thousand dollars is invested in each of a sample of 35 income and 40 growth funds.The mean increase for a two-year period for the income funds is $900.For the growth funds the mean increase is $875.Income funds have a population standard deviation of $35;growth funds have a population standard deviation of $45.At the 0.05 significance level,is there a difference in the mean yields of the two funds? What is the null hypothesis? __________________

If two dependent samples of size 20 are used to test the difference between the means,the degrees of freedom for a t-statistic is 19.

For hypotheses that compare two population means,what test statistic if used when the population standard deviations are known?

In a market test of a new chocolate raspberry coffee,a poll of 400 people from Dobbs Ferry showed 250 preferred the new coffee.In Irvington,170 out of 350 people preferred the new coffee.To test the hypothesis that there is no difference in preferences between the two villages,what is the alternate hypothesis?

Accounting procedures allow a business to evaluate their inventory at LIFO (Last In First Out)or FIFO (First In First Out).A manufacturer evaluated its finished goods inventory (in $ thousands)for five products both ways.Based on the following results,is LIFO more effective in keeping the value of his inventory lower? What is the alternate hypothesis?

The results of a mathematics placement exam at two different campuses of Mercy College follow: What is the computed value of the test statistic?

The pooled estimate of the proportion is found by dividing the total number of samples by the total number of successes.

Accounting procedures allow a business to evaluate their inventory at LIFO (Last In First Out)or FIFO (First In First Out).A manufacturer evaluated its finished goods inventory (in $ thousands)for five products both ways.Based on the following results,is LIFO more effective in keeping the value of his inventory lower? If you use the 5% level of significance,what is the critical t value?

If we are testing for the difference between two population proportions,it is assumed that the two populations are approximately normal and have equal variances.

If we are testing for the difference between two population means,it is assumed that the sample observations from one population are independent of the sample observations from the other population.