Question 1

When testing  , the observed value of the z-score was found to be -2.15. The p-value for this test would be:
A) .0158
B) .0316
C) .1582
D) .9842
E) .9684

Accepted Answer

The answer of When testing  , the observed value...

Question 2

When testing for differences between the means of two dependent populations, we can use either a one-tailed or two-tailed test.

Accepted Answer

This is true. Both one-tailed and two-tailed tests can be used in this case, depending on the hypothesis being tested. For example, if the hypothesis is that population A has a higher mean than population B, then a one-tailed test in the direction of greater-than would be used. If the hypothesis is simply that the means of the two populations are different, then a two-tailed test would be used.

Question 3

The expected value of  is E (  ) =  .

Accepted Answer

This statement uses the concept of linearity of expectation where E(aX+b) = aE(X) + b. Here, a and b are constants while X is a random variable. Since 11eb6b9e_063a_496c_8d9d_53abd7b5422b_TB8220_11 and 11eb6b9e_063a_496d_8d9d_af74a44116dc_TB8220_11 differ only in one hexadecimal digit, we can see that their difference is a constant. Therefore, their expected values will also differ in only that constant, and E(11eb6b9e_063a_496d_8d9d_af74a44116dc_TB8220_11) = E(11eb6b9e_063a_496c_8d9d_53abd7b5422b_TB8220_11) + constant. Thus, the statement is true.

Question 4

A university investigation was conducted to determine whether women and men complete medical school in significantly different amounts of time, on the average. Two independent random samples were selected and the following summary information concerning times to completion of medical school computed:  Perform the appropriate test of hypothesis to determine whether there is a significant difference in time to completion of medical school between women and men. Test using  = 0.05.
Test statistic = ______________
Critical Value(s) = ______________
Conclusion: ______________
Interpretation: __________________________________________
Find the p-value associated with the test above.
p-value = ______________

Accepted Answer

The answer of A university investigation was conducted to determine...

Question 5

The sampling distribution of  is normal if the sampled populations are normal, and approximately normal if the populations are nonnormal and the sample sizes  and  are large.

Accepted Answer

This statement is correct according to the central limit theorem, which states that the sampling distribution of a large enough sample size will be approximately normal, regardless of the distribution of the population being sampled from.

Question 6

If you wish to construct a confidence interval estimate for the difference between two population means, an increase in the sample sizes used will result in:
A) a decrease in the critical value z
B) a narrower confidence interval
C) a wider confidence interval
D) a confidence interval that contains zero
E) a confidence interval that does not contain zero

Accepted Answer

As the sample sizes increase, the standard error of the difference in means decreases, resulting in a narrower confidence interval.

Question 7

An airline company would like to know if the average number of passengers on a flight in November is less than the average number of passengers on a flight in December. The results of random sampling are printed below.  Test the appropriate hypotheses using  = 0.01.
Test statistic = ______________
Critical Value(s) = ______________
Conclusion: ______________
Interpretation: __________________________________________

Accepted Answer

The answer of An airline company would like to know...

Question 8

When the necessary conditions are met, a two-tailed test is being conducted to test the difference between two population means, but your statistical software provides only a one-tail area of .036 as part of its output. The p-value for this test will be:
A) 0.018
B) 0.009
C) 0.072
D) 0.928
E) 0.964

Accepted Answer

The p-value for a two-tailed test is twice the one-tail area provided by the statistical software, so 2 * 0.036 = 0.072.

Question 9

If you wish to estimate the difference between two population means using two independent large samples, the 90% confidence interval estimate can be constructed using which of the following critical values?
A) 1.96
B) 2.33
C) 2.58
D) 1.645
E) 1.28

Accepted Answer

For a 90% confidence interval, the critical value for a standard normal distribution (Z-distribution) is 1.645.

Question 10

In testing the difference between two population means using two independent samples, the population standard deviations are assumed to be known and the calculated test statistic equals 2.56. If the test is two-tail and 5% level of significance has been specified, the conclusion should be to:
A) reject the null hypothesis
B) not to reject the null hypothesis
C) repeat using a one-tail test
D) choose two other independent samples
E) none of these

Accepted Answer

Since the calculated test statistic, 2.56, exceeds the critical value of 1.96 at the 5% level of significance for a two-tailed test, we reject the null hypothesis and conclude that there is a significant difference between the two population means.

Question 11

In testing the difference between two population means using two independent samples, the sampling distribution of the sample mean difference  is normal if:
A) the sample sizes are both greater than 30
B) the populations are normal
C) the populations are non-normal and the sample sizes are large
D) all of these
E) none of these

Accepted Answer

The answer of In testing the difference between two population...

Question 12

When testing  , the observed value of the z-score was found to be -2.15. Then, the p-value for this test would be:
A) .0136
B) .0158
C) .0316
D) .9864
E) 0.9842

Accepted Answer

The answer of When testing  , the observed value...

Question 13

Two independent samples of sizes 40 and 50 are randomly selected from two populations to test the difference between the population means  . The sampling distribution of the sample mean difference  is:
A) normally distributed
B) approximately normal
C) Student t-distributed with 88 degrees of freedom
D) approximately normal and student t-distributed with 88 degrees of freedom
E) none of these

Accepted Answer

The answer of Two independent samples of sizes 40 and...

Question 14

A social worker was interested in determining whether there is a significant difference in the average monthly cost per child for childcare outside the home between state supported facilities and privately owned facilities. Two independent random samples yielded the following information:  Perform the appropriate test of hypothesis to determine whether there is a significant difference in the average monthly cost per child for childcare between the two types of facilities. Use  = 0.10.
Test statistic = ______________
Critical Value(s) = ______________
Conclusion: ______________
Interpretation: __________________________________________
Find the p-value for the test above.
p-value = ______________

Accepted Answer

The answer of A social worker was interested in determining...

Question 15

When we test for differences between the means of two independent populations, we can only use a two-tailed test.

Accepted Answer

For testing differences between the means of two independent populations, we can use either a one-tailed test or a two-tailed test, depending on the research question and hypothesis.

Question 16

The variance of  is V (  ) =  .

Accepted Answer

The answer of The variance of  is V (...

Question 17

In testing  , the test statistic value z is found to be 1.69. What is the p-value of the test?
A) .0455
B) .0910
C) .1977
D) .3023
E) .3478

Accepted Answer

The answer of In testing  , the test statistic...

Question 18

Suppose that we reject the null hypothesis  at the 0 .05 level of significance. Then for which of the following  -values do we also reject the null hypothesis?
A) 0.02
B) 0.04
C) 0.06
D) 0.08
E) All of these.

Accepted Answer

The answer of Suppose that we reject the null hypothesis...

Question 19

When testing  , the observed value of the z-score was found to be -2.15. Then, the p-value for this test would be
A) .0158
B) .0316
C) .9842
D) .9864
E) .9964

Accepted Answer

The p-value is equal to the area under the curve to the left of the observed z-score. Looking at a standard normal distribution table or using a calculator, the area to the left of -2.15 is approximately 0.0316. Therefore, the p-value for this test is 0.0316 or 3.16%. The best choice for the answer is B.

Question 20

A computer laboratory manager was in charge of purchasing new battery packs for her lab of laptop computers. She narrowed her choices to two models that were available for her machines. Since the models cost about the same, she was interested in determining whether there was a difference in the average time the battery packs would function before needing to be recharged. She took two independent samples and computed the following summary information:  Perform the appropriate test of hypothesis to determine whether there is a significant difference in average functioning time before recharging between the two models of battery packs. Test using  = 0.10.
Test statistic = ______________
Critical Value(s) = ______________
Conclusion: ______________
Interpretation: __________________________________________
Find the p-value for the test above.
p-value = ______________

Accepted Answer

The answer of A computer laboratory manager was in charge...

Quiz 9: Large-Sample Tests of Hypotheses

When testing , the observed value of the z-score was found to be -2.15. The p-value for this test would be:

When testing for differences between the means of two dependent populations, we can use either a one-tailed or two-tailed test.

The expected value of is E ( ) = .

The sampling distribution of is normal if the sampled populations are normal, and approximately normal if the populations are nonnormal and the sample sizes and are large.

If you wish to construct a confidence interval estimate for the difference between two population means, an increase in the sample sizes used will result in:

When the necessary conditions are met, a two-tailed test is being conducted to test the difference between two population means, but your statistical software provides only a one-tail area of .036 as part of its output. The p-value for this test will be:

If you wish to estimate the difference between two population means using two independent large samples, the 90% confidence interval estimate can be constructed using which of the following critical values?

In testing the difference between two population means using two independent samples, the population standard deviations are assumed to be known and the calculated test statistic equals 2.56. If the test is two-tail and 5% level of significance has been specified, the conclusion should be to:

In testing the difference between two population means using two independent samples, the sampling distribution of the sample mean difference is normal if:

When testing , the observed value of the z-score was found to be -2.15. Then, the p-value for this test would be:

Two independent samples of sizes 40 and 50 are randomly selected from two populations to test the difference between the population means . The sampling distribution of the sample mean difference is:

When we test for differences between the means of two independent populations, we can only use a two-tailed test.

The variance of is V ( ) = .

In testing , the test statistic value z is found to be 1.69. What is the p-value of the test?

Suppose that we reject the null hypothesis at the 0 .05 level of significance. Then for which of the following -values do we also reject the null hypothesis?

When testing , the observed value of the z-score was found to be -2.15. Then, the p-value for this test would be