Exam 11: Two-Sample Tests of Hypothesis

A study by a bank compared the average savings of customers who were depositors for three years or less,with those who had been depositors for more than three years.The results of a sample are: What is the p-value if $\alpha$ = .05 and the test statistic is 3.15? _____

How is a pooled estimate of the population proportion represented?

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 null hypothesis?

For a hypothesis test comparing two population means,the combined degrees of freedom are 24.Which of the following statements about the two sample sizes is NOT true? Assume the population standard deviations are equal.

Using two independent samples,we test for a hypothesized difference between two population means.The population standard deviations are equal.The number in the first sample is fifteen and the number in the second sample is twelve.How many degrees of freedom are associated with the critical value?

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. If we test the null hypothesis at the 1% level of significance,what is the decision?

What is the purpose of pooling the sample variances when testing the difference between two population means? ___________

The results of a mathematics placement exam at two different campuses of Mercy College follow: Given that the two population standard deviations are known,what is the p-value if the computed test statistic is 4.1?

In one class,a statistics professor wants to compare grades on the first and second exams.This is an example of paired or dependent observations.

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 degree of freedom?

Suppose we test the difference between two proportions at the 0.05 level of significance.If the computed z is -1.07,what is our decision?

The paired difference test has (n₁ + n₂ - 2)degrees of freedom.

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

What is the purpose of pooling the sample proportions when testing the difference between two population proportions? ___________

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: Edne: 5,8,7,6,9 and 7 Orno: 8,10,7,11,9,12,14 and 9 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.

If we are testing for the difference between two population means and assume that the two populations have equal and unknown standard deviations,the standard deviations are pooled to compute the best estimated variance.

If the null hypothesis that two means are equal is true,where will 97% of the computed z-values lie between?

Of 250 adults who tried a new multi-grain cereal,"Wow!",187 rated it excellent;of 100 children sampled,66 rated it excellent.What test statistic should we use?

If two independent samples of size 10 are used to test the difference between the means,the degrees of freedom for a t-statistic are 18.

If the null hypothesis states that there is no difference between the mean income of males and the mean income of females,then the test is one-tailed.