Deck 9: Statistical Inference: Hypothesis Testing for Single Populations

Question 1

When a false null hypothesis is rejected,the researcher has made a Type II error.

Answer 1

False

Question 2

Generally speaking,the hypotheses that business researchers want to prove are stated in the alternative hypothesis.

Answer 2

True

Question 3

Reach a statistical conclusion in hypothesis testing problems about a population proportion using the z statistic.

Answer 3

Included in this chapter were hypothesis tests for a single mean when σ is known and when σ is unknown,a test of a single population proportion,and a test for a population variance.Three different analytic approaches were presented: (1)the standard method, (2)the p value method,and (3)the critical value method.

Question 4

Hypotheses are tentative explanations of a principle operating in nature.

Question 5

Reach a statistical conclusion in hypothesis testing problems about a population mean with a known population standard deviation using the z statistic.

Question 6

Reach a statistical conclusion in hypothesis testing problems about a population variance using the chi-square statistic.

Question 7

When a true null hypothesis is rejected,the researcher has made a Type I error.

Question 8

Whenever hypotheses are established such that the alternative hypothesis is "not equal to",the hypothesis test would be a two-tailed test.

Question 9

Power is equal to (1 - $\beta$ ),the probability of a test rejecting the null hypothesis that is indeed false.

Question 10

The rejection region for a hypothesis test becomes smaller if the level of significance is changed from 0.01 to 0.05.

Question 11

Whenever hypotheses are established such that the alternative hypothesis is ">",then this would be a two-tailed test.

Question 12

Reach a statistical conclusion in hypothesis testing problems about a population mean with an unknown population standard deviation using the t statistic.

Question 13

The first step in testing a hypothesis is to establish a true null hypothesis and a false alternative hypothesis.

Question 14

Develop both one- and two-tailed null and alternative hypotheses that can be tested in a business setting by examining the rejection and nonrejection regions in light of Type I and Type II errors.

Question 15

The probability of committing a Type I error is called the power of the test.

Question 16

In testing hypotheses,the researcher initially assumes that the alternative hypothesis is true and uses the sample data to reject it.

Question 17

The null and the alternative hypotheses must be mutually exclusive and collectively exhaustive.

Question 18

When a researcher fails to reject a false null hypothesis,a Type II error has been committed.

Question 19

The rejection and nonrejection regions are divided by a point called the critical value.

Question 20

Solve for possible Type II errors when failing to reject the null hypothesis.

Question 21

In performing a hypothesis test where the null hypothesis is that the population mean is 23 against the alternative hypothesis that the population mean is not equal to 23,a random sample of 17 items is selected.The sample mean is 24.6 and the sample standard deviation is 3.3.It can be assumed that the population is normally distributed.The degrees of freedom associated with this are ___.

A)17
B)16
C)15
D)2
E)1

Question 22

In a two-tailed hypothesis about a population mean with a sample size of 100 and α = 0.05,the rejection region would be ___.

A)z > 1.64
B)z > 1.96
C)z < -1.96 and z > 1.96
D)z < -1.64 and z > 1.64
E)z < -2.33 and z > 2.33

Question 23

A company produces an item that is supposed to have a six centimetre hole punched in the centre.A quality control inspector is concerned that the machine which punches the hole is "out-of-control" (hole is too large or too small).In an effort to test this,the inspector is going to gather a sample punched by the machine and measure the diameter of the hole.The alternative hypothesis used to statistical test to determine if the machine is out-of-control is

A)the mean diameter is > 6 centimetres.
B)the mean diameter is < 6 centimetres.
C)the mean diameter is = 6 centimetres.
D)the mean diameter is ≠ 6 centimetres.
E)the mean diameter is ≥ 6 centimetres.

Question 24

Suppose the alternative hypothesis in a hypothesis test is "the population mean is greater than 60".If the sample size is 80 and alpha = .01,the critical value of z is ___.

A)2.575
B)-2.575
C)2.33
D)-2.33
E)2.45

Question 25

Consider the following null and alternative hypotheses. H_o: µ = 67
H_a: µ $\neq$ 67
These hypotheses ___.

A)indicate a one-tailed test with a rejection area in the right tail
B)indicate a one-tailed test with a rejection area in the left tail
C)indicate a two-tailed test
D)are established incorrectly
E)are not mutually exclusive

Question 26

A researcher is testing a hypothesis of a single mean.The critical z value for $\alpha$ = .05 and a two-tailed test is +1.96.The observed z value from sample data is -1.85.The decision made by the researcher based on this information is to ___ the null hypothesis.

A)reject
B)not reject
C)redefine
D)change the alternate hypothesis into
E)restate the null hypothesis

Question 27

A researcher is testing a hypothesis of a single mean.The critical z value for $\alpha$ = .05 and a two-tailed test is +1.96.The observed z value from sample data is -2.11.The decision made by the researcher based on this information is to ___ the null hypothesis.

A)reject
B)not reject
C)redefine
D)change the alternate hypothesis into
E)restate the null hypothesis

Question 28

Jennifer Cantu,VP of Customer Services at Tri-City Auto Insurance Inc. ,monitors the claims processing time of the claims division.Her standard includes "a mean processing time of 5 days or less." Each week,her staff checks for compliance by analyzing a random sample of 60 claims.Jennifer's null hypothesis is ___.

A) $\mu$ > 5
B) $\sigma$ > 5
C)n = 60
D) $\mu$ < 5
E) $\mu$ = 5

Question 29

A researcher is testing a hypothesis of a single mean.The critical z value for $\alpha$ = .05 and a two-tailed test is +1.96.The observed z value from sample data is 2.85.The decision made by the researcher based on this information is to ___ the null hypothesis.

A)reject
B)not reject
C)redefine
D)change the alternate hypothesis into
E)restate the null hypothesis

Question 30

Consider the following null and alternative hypotheses. H_o: µ $\ge$ 67
H_a: µ < 67
These hypotheses ___.

A)indicate a one-tailed test with a rejection area in the right tail
B)indicate a one-tailed test with a rejection area in the left tail
C)indicate a two-tailed test
D)are established incorrectly
E)are not mutually exclusive

Question 31

If the researcher computes the probability of the calculated statistic and compares it to alpha,the level of significance to reach a decision,the researcher is using the p-value method for testing the hypotheses.

Question 32

Suppose you are testing the null hypothesis that a population mean is less than or equal to 80,against the alternative hypothesis that the population mean is greater than 80.If the sample size is 49 and alpha = .10,the critical value of z is ___.

A)1.645
B)-1.645
C)1.28
D)-1.28
E)2.33

Question 33

Suppose you are testing the null hypothesis that a population mean is less than or equal to 80,against the alternative hypothesis that the population mean is greater than 80.The sample size is 49 and alpha =.05.If the sample mean is 84 and the population standard deviation is 14,the observed z value is ___.

A)2
B)-2
C)14
D)-14
E)49

Question 34

Suppose the alternative hypothesis in a hypothesis test is: "the population mean is less than 60".If the sample size is 50 and alpha =.05,the critical value of z is ___.

A)1.645
B)-1.645
C)1.96
D)-1.96
E)2.05

Question 35

In performing a hypothesis test where the null hypothesis is that the population mean is 4.8 against the alternative hypothesis that the population mean is not equal to 4.8,a random sample of 25 items is selected.The sample mean is 4.1 and the sample standard deviation is 1.4.It can be assumed that the population is normally distributed.The degrees of freedom associated with this are ___.

A)25
B)24
C)26
D)2
E)1

Question 36

In a two-tailed hypothesis about a population mean with a sample size of 100 and alpha = 0.10,the rejection region would be ___.

A)z > 1.64
B)z > 1.28
C)z < -1.28 and z > 1.28
D)z < -1.645 and z > 1.645
E)z < -2.33 and z > 2.33

Question 37

Consider the following null and alternative hypotheses: H_o: µ $\le$ 67
H_a: µ > 67
These hypotheses ___.

A)indicate a one-tailed test with a rejection area in the right tail
B)indicate a one-tailed test with a rejection area in the left tail
C)indicate a two-tailed test
D)are established incorrectly
E)are not mutually exclusive

Question 38

If a null hypothesis was not rejected at the 0.10 level of significance,it will be rejected at a 0.05 level of significance based on the same sample results.

Question 39

A researcher is testing a hypothesis of a single mean.The critical z value for $\alpha$ = .05 and an one?tailed test is 1.645.The observed z value from sample data is 1.13.The decision made by the researcher based on this information is to ___ the null hypothesis.

A)reject
B)not reject
C)redefine
D)change the alternate hypothesis into
E)restate the null hypothesis

Question 40

Suppose you are testing the null hypothesis that a population mean is greater than or equal to 60,against the alternative hypothesis that the population mean is less than 60.The sample size is 64 and $\alpha$ = .05.If the sample mean is 58 and the population standard deviation is 16,the observed z value is ___.

A)-1
B)1
C)-8
D)8
E)58

Question 41

In performing hypothesis tests about the population mean,the population standard deviation should be used if it is known.If it is not known,which of the following statistical test should be used?

A)z test of a population mean
B)t test of a population mean
C)z test of a population proportion
D) $\chi$ ² test of a population variance
E)t test of a population proportion

Question 42

In performing hypothesis tests about the population mean,the population standard deviation should be used if it is known.If it is not known,a t test can be used to test the mean if ___.

A)the sample size is at least thirty
B)the sample is random
C)the population mean is known
D)the population is normally distributed
E)the population is chi-square distributed

Question 43

In performing a hypothesis test where the null hypothesis is that the population mean is 6.9 against the alternative hypothesis that the population mean is not equal to 6.9,a random sample of 16 items is selected.The sample mean is 7.1 and the sample standard deviation is 2.4.It can be assumed that the population is normally distributed.The observed "t" value for this problem is ___.

A)0.05
B)0.20
C)0.33
D)1.33
E)1.43

Question 44

Consider the following null and alternative hypotheses: H_o: p $\le$ 0.16
H_a: p > 0.16
These hypotheses ___.

A)indicate a one-tailed test with a rejection area in the right tail
B)indicate a one-tailed test with a rejection area in the left tail
C)indicate a two-tailed test
D)are established incorrectly
E)are not mutually exclusive

Question 45

Consider the following null and alternative hypotheses: H_o: p $\ge$ 0.16
H_a: p < 0.16
These hypotheses ___.

A)indicate a one-tailed test with a rejection area in the right tail
B)indicate a one-tailed test with a rejection area in the left tail
C)indicate a two-tailed test
D)are established incorrectly
E)are not mutually exclusive

Question 46

The diameter of 3.5 centimetre discs is normally distributed.Periodically,quality control inspectors at Winnipeg Discs randomly select a sample of 16 discs.If the mean diameter of the discs is too large or too small the disc punch is shut down for adjustment;otherwise,the punching process continues.The last sample showed a mean and standard deviation of 3.49 and 0.08 centimetres,respectively.Using $\alpha$ = 0.05,the appropriate decision is ___.

A)reject the null hypothesis and shut down the punch
B)reject the null hypothesis and do not shut down the punch
C)do not reject the null hypothesis and shut down the punch
D)do not reject the null hypothesis and do not shut down the punch
E)do nothing

Question 47

In performing a hypothesis test where the null hypothesis is that the population mean is 6.9 against the alternative hypothesis that the population mean is not equal to 6.9,a random sample of 16 items is selected.The sample mean is 7.1 and the sample standard deviation is 2.4.It can be assumed that the population is normally distributed.The level of significance is selected as 0.05.The decision rule for this problem is to reject the null hypothesis if the observed "t" value is ___.

A)less than -2.131 or greater than 2.131
B)less than -1.761 or greater than 1.761
C)less than -1.753 or greater than 1.753
D)less than -2.120 or greater than 2.120
E)less than -3.120 or greater than 3.120

Question 48

A political scientist wants to prove that a candidate is currently carrying more than 60% of the vote in the riding.She has her assistants randomly sample 200 eligible voters in the riding by telephone and only 90 declare that they support her candidate.The observed z value for this problem is ___.

A)-4.33
B)4.33
C)0.45
D)-.31
E)2.33

Question 49

A company believes that it controls more than 30% of the total market share for one of its products.To prove this belief,a random sample of 144 purchases of this product is contacted.It is found that 50 of the 144 purchased this company's brand of the product.If a researcher wants to conduct a statistical test for this problem,the alternative hypothesis would be ___.

A)the population proportion is less than 0.30
B)the population proportion is greater than 0.30
C)the population proportion is not equal to 0.30
D)the population mean is less than 40
E)the population mean is greater than 40

Question 50

Ophelia O'Brien,VP of Consumer Credit of Credit First Banks (CFB),monitors the default rate on personal loans at the CFB member banks.One of her standards is "no more than 5% of personal loans should be in default." On each Friday,the default rate is calculated for a sample of 500 personal loans.Last Friday's sample contained 30 defaulted loans.Ophelia's null hypothesis is ___.

A)p > 0.05
B)p = 0.05
C)n = 30
D)n = 500
E)n = 0.05

Question 51

In performing a hypothesis test where the null hypothesis is that the population mean is 6.9 against the alternative hypothesis that the population mean is not equal to 6.9,a random sample of 16 items is selected.The sample mean is 7.1 and the sample standard deviation is 2.4.It can be assumed that the population is normally distributed.The level of significance is selected as 0.05.The table "t" value for this problem is ___.

A)1.753
B)2.947
C)2.120
D)2.131
E)2.311

Question 52

Consider the following null and alternative hypotheses: H_o: p = 0.16
H_a: p $\neq$ 0.16
These hypotheses ___.

A)indicate a one-tailed test with a rejection area in the right tail
B)indicate a one-tailed test with a rejection area in the left tail
C)indicate a two-tailed test
D)are established incorrectly
E)are not mutually exclusive

Question 53

Suppose a researcher is testing a null hypothesis that $\mu$ = 61.A random sample of n = 36 is taken resulting in a sample mean of 63 and s = 9.The observed t value is ___.

A)-0.22
B)0.22
C)1.33
D)8.08
E)7.58

Question 54

A company believes that it controls more than 30% of the total market share for one of its products.To prove this belief,a random sample of 144 purchases of this product is contacted.It is found that 50 of the 144 purchased this company's brand of the product.If a researcher wants to conduct a statistical test for this problem,the observed z value would be ___.

A)0.05
B)0.103
C)0.35
D)1.24
E)1.67

Question 55

The diameter of 3.5 centimetre discs is normally distributed.Periodically,quality control inspectors at Winnipeg Discs randomly select a sample of 16 discs.If the mean diameter of the discs is too large or too small the disc punch is shut down for adjustment;otherwise,the punching process continues.The null hypothesis is ___.

A)n $\neq$ 16
B)n = 16
C) $\mu$ = 3.5
D) $\mu$ $\neq$ 3.5
E) $\mu$ ≥ 3.5

Question 56

In performing a hypothesis test where the null hypothesis is that the population mean is 4.8 against the alternative hypothesis that the population mean is not equal to 4.8,a random sample of 25 items is selected.The sample mean is 4.1 and the sample standard deviation is 1.4.It can be assumed that the population is normally distributed.The level of significance is selected to be 0.10.The table "t" value for this problem is ___.

A)1.318
B)1.711
C)2.492
D)2.797
E)3.227

Question 57

The diameter of 3.5 centimetre discs is normally distributed.Periodically,quality control inspectors at Winnipeg Discs randomly select a sample of 16 discs.If the mean diameter of the discs is too large or too small the disc punch is shut down for adjustment;otherwise,the punching process continues.The last sample showed a mean and standard deviation of 3.49 and 0.08 centimetres,respectively.Using $\alpha$ = 0.05,the critical "t" values are ___.

A)-2.120 and 2.120
B)-2.131 and 2.131
C)-1.753 and 1.753
D)-1.746 and 1.746
E)-2.567 and 2.567

Question 58

A company believes that it controls more than 30% of the total market share for one of its products.To prove this belief,a random sample of 144 purchases of this product is contacted.It is found that 50 of the 144 purchased this company's brand of the product.If a researcher wants to conduct a statistical test for this problem,the test would be ___.

A)a one-tailed test
B)a two-tailed test
C)an alpha test
D)a finite population test
E)a finite sample test

Question 59

In performing a hypothesis test where the null hypothesis is that the population mean is 4.8 against the alternative hypothesis that the population mean is not equal to 4.8,a random sample of 25 items is selected.The sample mean is 4.1 and the sample standard deviation is 1.4.It can be assumed that the population is normally distributed.The observed "t" value for this problem is ___.

A)-12.5
B)12.5
C)-2.5
D)-0.7
E)0.7

Question 60

The diameter of 3.5 centimetre discs is normally distributed.Periodically,quality control inspectors at Winnipeg Discs randomly select a sample of 16 discs.If the mean diameter of the discs is too large or too small the disc punch is shut down for adjustment;otherwise,the punching process continues.The last sample showed a mean and standard deviation of 3.55 and 0.08 centimetres,respectively.Using $\alpha$ = 0.05,the appropriate decision is ___.

A)reject the null hypothesis and shut down the punch
B)reject the null hypothesis and do not shut down the punch
C)do not reject the null hypothesis and shut down the punch
D)do not reject the null hypothesis and do not shut down the punch
E)do nothing

Question 61

David Desreumaux,VP of Human Resources of Maritime Boat Manufacturing (MBM),is reviewing the employee training programs of MBM factories.Based on a recent census of personnel,David knows that the variance of worker training time in New Brunswick is 8,and he wonders if the variance in Nova Scotia is the same number.His staff randomly selected personnel files for 15 workers in Nova Scotia,and determined that their mean training time was 25 hours and that the standard deviation was 4 hours.Assume that worker training time is normally distributed in the population.Using $\alpha$ = 0.10,the appropriate decision is ___.

A)increase the sample size
B)reduce the sample size
C)do not reject the null hypothesis
D)maintain status quo
E)reject the null hypothesis

Question 62

Discrete Components Inc.manufactures a line of electrical resistors.Presently,the carbon composition line is producing 100 ohm resistors.The population variance of these resistors "must not exceed 4" to conform to industry standards.Periodically,the quality control inspectors check for conformity by randomly select 10 resistors from the line,and calculating the sample variance.The last sample had a variance of 4.36.Assume that the population is normally distributed.Using $\alpha$ = 0.05,the observed value of chi-square is ___.

A)1.74
B)1.94
C)10.90
D)9.81
E)8.91

Question 63

A null hypothesis is p > 0.65.To test this hypothesis,a sample of 400 is taken and alpha is set at 0.05.If the true proportion is p = 0.60,what is the probability of a Type II error?

A)0.17
B)0.45
C)0.95
D)0.67
E)0.33

Question 64

David Desreumaux,VP of Human Resources of Maritime Boat Manufacturing (MBM),is reviewing the employee training programs of MBM factories.Based on a recent census of personnel,David knows that the variance of worker training time in New Brunswick is 8,and he wonders if the variance in Nova Scotia is the same number.His staff randomly selected personnel files for 15 workers in Nova Scotia,and determined that their mean training time was 25 hours and that the standard deviation was 4 hours.Assume that worker training time is normally distributed in the population.Using $\alpha$ = 0.10,the observed value of chi-square is ___.

A)28.00
B)30.00
C)56.00
D)60.00
E)65.00

Question 65

Discrete Components Inc.manufactures a line of electrical resistors.Presently,the carbon composition line is producing 100 ohm resistors.The population variance of these resistors "must not exceed 4" to conform to industry standards.Periodically,the quality control inspectors check for conformity by randomly select 10 resistors from the line,and calculating the sample variance.The last sample had a variance of 4.36.Assume that the population is normally distributed.Using $\alpha$ = 0.05,the appropriate decision is ___.

A)increase the sample size
B)reduce the sample size
C)reject the null hypothesis
D)do not reject the null hypothesis
E)maintain status quo

Question 66

Discrete Components Inc.manufactures a line of electrical resistors.Presently,the carbon composition line is producing 100 ohm resistors.The population variance of these resistors "must not exceed 4" to conform to industry standards.Periodically,the quality control inspectors check for conformity by randomly select 10 resistors from the line,and calculating the sample variance.The last sample had a variance of 4.36.Assume that the population is normally distributed.Using $\alpha$ = 0.05,the critical value of chi-square is ___.

A)18.31
B)16.92
C)3.94
D)3.33
E)19.82

Question 67

The executives of CareFree Insurance Inc.feel that "a majority of our employees perceive a participatory management style at CareFree." A random sample of 200 CareFree employees is selected to test this hypothesis at the 0.05 level of significance.Eighty employees rate the management as participatory.The null hypothesis is ___.

A)n = 30
B)n = 200
C)p = 0.50
D)p < 0.50
E)n > 200

Question 68

Elwin Osbourne,CIO at GFS,Inc. ,suspects that at least 25% of email messages sent by GFS employees are not business related.A random sample of 300 email messages was selected to test this hypothesis at the 0.01 level of significance.Fifty-four of the messages were not business related.The null hypothesis is ____.

A) $\beta$ = 30
B)n = 300
C)p < 0.25
D)p ≠ 0.25
E)p = 0.25

Question 69

Ophelia O'Brien,VP of Consumer Credit of Credit First Banks (CFB),monitors the default rate on personal loans at the CFB member banks.One of her standards is "no more than 5% of personal loans should be in default." On each Friday,the default rate is calculated for a sample of 500 personal loans.Last Friday's sample contained 38 defaulted loans.Using $\alpha$ = 0.10,the appropriate decision is ___.

A)reduce the sample size
B)increase the sample size
C)reject the null hypothesis
D)do not reject the null hypothesis
E)do nothing

Question 70

David Desreumaux,VP of Human Resources of Maritime Boat Manufacturing (MBM),is reviewing the employee training programs of MBM factories.Based on a recent census of personnel,David knows that the variance of worker training time in New Brunswick is 8,and he wonders if the variance in Nova Scotia is the same number.His staff randomly selected personnel files for 15 workers in Nova Scotia,and determined that their mean training time was 25 hours and that the standard deviation was 4 hours.Assume that worker training time is normally distributed in the population.Using $\alpha$ = 0.10,the null hypothesis is ___.

A) $\mu$ = 25
B) $\sigma$ ² = 8
C) $\sigma$ ² = 4
D) $\sigma$ ² $\le$ 8
E)s² = 16

Question 71

Ophelia O'Brien,VP of Consumer Credit of Credit First Banks (CFB),monitors the default rate on personal loans at the CFB member banks.One of her standards is "no more than 5% of personal loans should be in default." On each Friday,the default rate is calculated for a sample of 500 personal loans.Last Friday's sample contained 30 defaulted loans.Using $\alpha$ = 0.10,the observed z value is ___.

A)1.03
B)-1.03
C)0.046
D)-0.046
E)1.33

Question 72

The executives of CareFree Insurance,Inc.feel that "a majority of our employees perceive a participatory management style at CareFree." A random sample of 200 CareFree employees is selected to test this hypothesis at the 0.05 level of significance.Eighty employees rate the management as participatory.The appropriate decision is ___.

A)do not reject the null hypothesis
B)reject the null hypothesis
C)reduce the sample size
D)increase the sample size
E)do nothing

Question 73

Ophelia O'Brien,VP of Consumer Credit of Credit First Banks (CFB),monitors the default rate on personal loans at the CFB member banks.One of her standards is "no more than 5% of personal loans should be in default." On each Friday,the default rate is calculated for a sample of 500 personal loans.Last Friday's sample contained 30 defaulted loans.Using $\alpha$ = 0.10,the appropriate decision is ___.

A)reduce the sample size
B)increase the sample size
C)reject the null hypothesis
D)do not reject the null hypothesis
E)do nothing

Question 74

Elwin Osbourne,CIO at GFS,Inc. ,suspects that at least 25% of email messages sent by GFS employees are not business related.A random sample of 300 email messages was selected to test this hypothesis at the 0.01 level of significance.Fifty-four of the messages were not business related.The appropriate decision is __.

A)increase the sample size
B)gather more data
C)reject the null hypothesis
D)do not reject the null hypothesis
E)maintain status quo

Question 75

The executives of CareFree Insurance,Inc.feel that "a majority of our employees perceive a participatory management style at CareFree." A random sample of 200 CareFree employees is selected to test this hypothesis at the 0.05 level of significance.Ninety employees rate the management as participatory.The appropriate decision is ___.

A)do not reject the null hypothesis
B)reject the null hypothesis
C)reduce the sample size
D)increase the sample size
E)maintain status quo

Question 76

Discrete Components Inc.manufactures a line of electrical resistors.Presently,the carbon composition line is producing 100 ohm resistors.The population variance of these resistors "must not exceed 4" to conform to industry standards.Periodically,the quality control inspectors check for conformity by randomly select 10 resistors from the line,and calculating the sample variance.The last sample had a variance of 4.36.Assume that the population is normally distributed.Using $\alpha$ = 0.05,the null hypothesis is ___.

A) $\mu$ = 100
B) $\sigma$ $\le$ 10
C)s² $\ge$ 4
D) $\sigma$ ² = 4
E)n = 100

Question 77

Ophelia O'Brien,VP of Consumer Credit of Credit First Banks (CFB),monitors the default rate on personal loans at the CFB member banks.One of her standards is "no more than 5% of personal loans should be in default." On each Friday,the default rate is calculated for a sample of 500 personal loans.Last Friday's sample contained 30 defaulted loans.Using $\alpha$ = 0.10,the critical z value is ___.

A)1.645
B)-1.645
C)1.28
D)-1.28
E)2.28

Question 78

Elwin Osbourne,CIO at GFS,Inc. ,suspects that at least 25% of email messages sent by GFS employees are not business related.A random sample of 300 email messages was selected to test this hypothesis at the 0.01 level of significance.Sixty of the messages were not business related.The appropriate decision is ___.

A)increase the sample size
B)gather more data
C)maintain status quo
D)do not reject the null hypothesis
E)reject the null hypothesis

Question 79

David Desreumaux,VP of Human Resources of Maritime Boat Manufacturing (MBM),is reviewing the employee training programs of MBM factories.Based on a recent census of personnel,David knows that the variance of worker training time in New Brunswick is 8,and he wonders if the variance in Nova Scotia is the same number.His staff randomly selected personnel files for 15 workers in Nova Scotia,and determined that their mean training time was 25 hours and that the standard deviation was 4 hours.Assume that worker training time is normally distributed in the population.Using $\alpha$ = 0.10,the critical values of chi-square are ___.

A)7.96 and 26.30
B)6.57 and 23.68
C)-1.96 and 1.96
D)-1.645 and 1.645
E)-6.57 and 23.68