Exam 11: Two-Sample Tests of Hypothesis

To compare the effect of weather on sales of soft drinks, a distributor surveyed people in two regions of the country and asked if they purchased soft drinks in the last month. The following are the results. The distributor would like to know if there is a difference in sales between the two regions. What is the alternate hypothesis?

A company is researching the effectiveness of a new website design to decrease the time to access a website. Five website users were randomly selected, and their times (in seconds) to access the website with the old and new designs were recorded. To compare the times, they computed (new website design time - old website design time). The results follow. What is the alternative hypothesis?

Accounting procedures allow a business to evaluate their inventory costs based on two methods: LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated its finished goods inventory (in $000s) for five products with the LIFO and FIFO methods. To analyze the difference, they computed (FIFO - LIFO) for each product. Based on the following results, does the LIFO method result in a lower cost of inventory than the FIFO method? What is the null hypothesis?

For a hypothesis comparing two population means, H₀: μ₁ ≤ μ_2, what is the critical value for a one-tailed hypothesis test, using a 5% significance level, with both sample sizes equal to 13? Assume the population standard deviations are equal.

When the population standard deviations are equal but unknown, a test for the differences between two populations assumes that the populations are _____________ distributed.

Accounting procedures allow a business to evaluate their inventory costs based on two methods: LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated its finished goods inventory (in $000s) for five products with the LIFO and FIFO methods. To analyze the difference, they computed (FIFO - LIFO) for each product. Based on the following results, does the LIFO method result in a lower cost of inventory than the FIFO method? What is the alternate hypothesis?

Assuming the population variances are known, the population variance of the difference between two means is _____________.

A committee that is 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 test if the reactions to the survey for office and plant personnel were the same, 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. What is the value of the test statistic? Round to two decimal places.

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

To compare the effect of weather on sales of soft drinks, a distributor surveyed people in two regions of the country and asked if they purchased soft drinks in the last month. The following are the results. The distributor would like to know if there is a difference in sales between the two regions. What is the value of the test statistic?

If we are testing for the difference between two population means and assume that the two populations have equal but unknown standard deviations, then the test has ________ degrees of freedom.

When testing the hypothesized equality of two population means, the implied null hypothesis is ____________.

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 sample standard deviation of $35; growth funds have a sample standard deviation of $45. Assume that the population standard deviations are equal. At the 0.05 significance level, is there a difference in the mean yields of the two funds? What decision is made about the null hypothesis using an α = 0.05?

Accounting procedures allow a business to evaluate their inventory costs based on two methods: LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated its finished goods inventory (in $000s) for five products with the LIFO and FIFO methods. To analyze the difference, they computed (FIFO - LIFO) for each product. Based on the following results, does the LIFO method result in a lower cost of inventory than the FIFO method? If you use the 5% level of significance, what is the critical t value?

A company is researching the effectiveness of a new website design to decrease the time to access a website. Five website users were randomly selected, and their times (in seconds) to access the website with the old and new designs were recorded. To compare the times, they computed (new website design time - old website design time). The results follow. For a 0.01 significance level, what is the critical value?

When dependent samples are used to test for differences in the means, we compute ________________ differences.

Accounting procedures allow a business to evaluate their inventory costs based on two methods: LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated its finished goods inventory (in $000s) for five products with the LIFO and FIFO methods. To analyze the difference, they computed (FIFO - LIFO) for each product. Based on the following results, does the LIFO method result in a lower cost of inventory than the FIFO method? What are the degrees of freedom?

A recent study focused on the amount of money single men and women save monthly. The information is summarized next. Assume that the population standard deviations are equal. At the .01 significance level, what is the conclusion about the way women and men save?

To compare the effect of weather on sales of soft drinks, a distributor surveyed people in two regions of the country and asked if they purchased soft drinks in the last month. The following are the results. The distributor would like to know if there is a difference in sales between the two regions. Test the hypothesis with a 0.01 significance level. What is our decision?

The net weights (in grams) of a sample of bottles filled by a machine manufactured by Edne, and the net weights of a sample filled by a similar machine manufactured by Orno, Inc., are: Testing the claim at the 0.05 level that the mean weight of the bottles filled by the Orno machine is greater than the mean weight of the bottles filled by the Edne machine, what is the critical value? Assume equal standard deviations for both samples.