Deck 10: Statistical Inferences About Two Populations

Question 1

When testing for the difference between two population proportions we use the pooled estimate of the proportion.

Answer 1

True

Question 2

To test hypotheses about the equality of two population variances,the ratio of the variances of the samples from the two populations is tested using the F test.

Answer 2

True

Question 3

In order to construct an interval estimate for the difference in the means of two normally distributed populations with unknown but equal variances,using two independent samples of size n₁ and n₂,we must use a t distribution with (n₁ + n₂ − 2)degrees of freedom.

Answer 3

True

Question 4

In order to construct an interval estimate for the difference in the means of two normally distributed populations with unknown but equal variances,using two independent samples of size n₁ and n₂,we must use a t distribution with (n₁ + n₂ -1)degrees of freedom.

Question 5

In conducting a matched-pairs hypothesis test,the null and alternative hypotheses always represent one-tailed tests.

Question 6

When finding a confidence interval for the difference between two population proportions we use the pooled estimate of the proportion.

Question 7

If the variances of the two populations are not equal,it is appropriate to use the "pooled" formula to determine the t-statistic for the hypothesis test of the difference in the two population means.

Question 8

If the populations are normally distributed but the population variances are unknown the z-statistic can be used as the basis for statistical inferences about the difference in two population means using two independent random samples.

Question 9

The difference in two sample means is normally distributed for sample sizes ≥ 30,only if the populations are normally distributed.

Question 10

If a 98% confidence interval for the difference in the two population means does not contain zero,then the null hypothesis of zero difference between the two population means cannot be rejected at a 0.02 level of significance.

Question 11

To determine if there is a difference in the speed of a wireless router from two different manufacturers a network manager will draw independent samples of wireless routers from the two manufacturers and compare the difference in the sample means for the connection speed.

Question 12

If the populations are normally distributed and the variances of the two populations are equal,it is appropriate to use the "pooled" formula to determine the t-statistic for the hypothesis test of the difference in the two population means.

Question 13

If the sample sizes are small,but the populations are normally distributed and the population variances are known,the z-statistic can be used as the basis for statistical inferences about the difference in two population means using two independent random samples.

Question 14

In a set of matched samples,each data value in one sample is related to or matched with a corresponding data value in the other sample.

Question 15

Sets of matched samples are also referred to as dependent samples.

Question 16

Hypothesis tests conducted on sets of matched samples are sometimes referred to as correlated t tests.

Question 17

If the sample sizes are greater than 30 and the population variances are known,the basis for statistical inferences about the difference in two population means using two independent random samples is the z-statistic,regardless of the shapes of the population distributions.

Question 18

If the populations are normally distributed but the population variances are unknown the t-statistic can be used as the basis for statistical inferences about the difference in two population means using two independent random samples.

Question 19

If the populations are normally distributed and the variances of the two populations are not equal,it is appropriate to use the "unpooled" formula to determine the t-statistic for the hypothesis test of the difference in the two population means.

Question 20

If a 90% confidence interval for the difference in the two population means contains zero,then the null hypothesis of zero difference between the two population means cannot be rejected at a 0.10 level of significance.

Question 21

A researcher is interested in testing to determine if the mean price of a casual lunch is different in the city than it is in the suburbs. The null hypothesis is that there is no difference in the population means (i.e.the difference is zero). The alternative hypothesis is that there is a difference (i.e.the difference is not equal to zero). He randomly selects a sample of 9 lunch tickets from the city population resulting in a mean of $14.30 and a standard deviation of $3.40.He randomly selects a sample of 14 lunch tickets from the suburban population resulting in a mean of $11.80 and a standard deviation $2.90.He is using an alpha value of .10 to conduct this test.Assuming that the populations are normally distributed,the critical t value from the table is _______.

A) 1.323
B) 1.721
C) 1.717
D) 1.321
E) 2.321

Question 22

The F test of two population variances is extremely robust to the violations of the assumption that the populations are normally distributed.

Question 23

Golf course designer Roberto Langabeer is evaluating two sites,Palmetto Dunes and Ocean Greens,for his next golf course. He wants to prove that Palmetto Dunes residents (population 1)play golf more often than Ocean Greens residents (population 2).Roberto plans to test this hypothesis using a random sample of 81 individuals from each suburb.His null hypothesis is __________.

A) $\sigma$ ₁² < $\sigma$ ₂²
B) $\mu$ ₁- $\mu$ ₂ >0
C) p₁ - p₂ = 0
D) $\mu$ ₁ - $\mu$ ₂ = 0
E) s₁ - s₂ = 0

Question 24

Lucy Baker is analyzing demographic characteristics of two television programs,American Idol (population 1)and 60 Minutes (population 2). Previous studies indicate no difference in the ages of the two audiences. (The mean age of each audience is the same.) Her staff randomly selected 100 people from each audience,and reported the following: ₁ = 43 years and ₂ = 45 years. Assume that $\sigma$ ₁ = 5 and $\sigma$ ₂ = 8. Assuming a two-tail test and $\alpha$ = .05,the observed z value is _________________.

A) -2.12
B) -2.25
C) -5.58
D) -15.38
E) -20.68

Question 25

A researcher wants to estimate the difference in the means of two populations.A random sample of 36 items from the first population results in a sample mean of 430. A random sample of 49 items from the second population results in a sample mean of 460. The population standard deviations are 120 for the first population and 140 for the second population. From this information,a 95% confidence interval for the difference in population means is _______.

A) -95.90 to 35.90
B) -85.44, 25.44
C) -76.53 to 16.53
D) -102.83 to 42.43
E) 98.45 to 125.48

Question 26

Lucy Baker is analyzing demographic characteristics of two television programs,American Idol (population 1)and 60 Minutes (population 2). Previous studies indicate no difference in the ages of the two audiences. (The mean age of each audience is the same.) Lucy plans to test this hypothesis using a random sample of 100 from each audience. Her alternate hypothesis is ____________.

A) $\mu$ ₁ - $\mu$ ₂ < 0
B) $\mu$ ₁ - $\mu$ ₂ > 0
C) $\mu$ ₁ - $\mu$ ₂ = 0
D) $\mu$ ₁ - $\mu$ ₂ $\neq$ 0
E) $\mu$ ₁ - $\mu$ ₂ = 1

Question 27

Golf course designer Roberto Langabeer is evaluating two sites,Palmetto Dunes and Ocean Greens,for his next golf course. He wants to prove that Palmetto Dunes residents (population 1)play golf more often than Ocean Greens residents (population 2). Roberto commissions a market survey to test this hypothesis.The market researcher used a random sample of individuals from each suburb,and reported the following: ₁ = 16 times per month and ₂ = 14 times per month. Assume that $\sigma$ ₁ = 4 and $\sigma$ ₂ = 3.With $\alpha$ = .01,the appropriate decision is _____________.

A) do nothing
B) reject the null hypothesis $\sigma$ ₁ < $\sigma$ ₂
C) accept the alternate hypothesis $\mu$ ₁- $\mu$ ₂ > 0
D) reject the alternate hypothesis n₁ = n₂ = 64
E) do not reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ = 0

Question 28

Lucy Baker is analyzing demographic characteristics of two television programs,American Idol (population 1)and 60 Minutes (population 2). Previous studies indicate no difference in the ages of the two audiences. (The mean age of each audience is the same.) Her staff randomly selected 100 people from each audience,and reported the following: ₁ = 43 years and ₂ = 45 years. Assume that $\sigma$ ₁ = 5 and $\sigma$ ₂ = 8. With a two-tail test and $\alpha$ = .05,the appropriate decision is _________________.

A) do not reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ = 0
B) reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ > 0
C) reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ = 0
D) do not reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ < 0
E) do nothing

Question 29

Lucy Baker is analyzing demographic characteristics of two television programs,American Idol (population 1)and 60 Minutes (population 2). Previous studies indicate no difference in the ages of the two audiences. (The mean age of each audience is the same.) Her staff randomly selected 100 people from each audience,and reported the following: ₁ = 43 years and ₂ = 45 years. Assume that $\sigma$ ₁ = 5 and $\sigma$ ₂ = 8. With a two-tail test and $\alpha$ = .05,the critical z values are _________________.

A) -1.64 and 1.64
B) -1.96 and 1.96
C) -2.33 and 2.33
D) -2.58 and 2.58
E) -2.97 and 2.97

Question 30

Golf course designer Roberto Langabeer is evaluating two sites,Palmetto Dunes and Ocean Greens,for his next golf course. He wants to prove that Palmetto Dunes residents (population 1)play golf more often than Ocean Greens residents (population 2). Roberto commissions a market survey to test this hypothesis.The market researcher used a random sample of 64 individuals from each suburb,and reported the following: ₁ = 15 times per month and ₂ = 14 times per month. Assume that $\sigma$ ₁ = 2 and $\sigma$ ₂ = 3. With $\alpha$ = .01,the critical z value is _________________.

A) -1.96
B) 1.96
C) -2.33
D) -1.33
E) 2.33

Question 31

A researcher is interested in testing to determine if the mean price of a casual lunch is different in the city than it is in the suburbs. The null hypothesis is that there is no difference in the population means (i.e.the difference is zero). The alternative hypothesis is that there is a difference (i.e.the difference is not equal to zero). He randomly selects a sample of 9 lunch tickets from the city population resulting in a mean of $14.30 and a standard deviation of $3.40.He randomly selects a sample of 14 lunch tickets from the suburban population resulting in a mean of $11.80 and a standard deviation $2.90.He is using an alpha value of .10 to conduct this test.Assuming that the populations are normally distributed and that the population variances are approximately equal,the degrees of freedom for this problem are _______.

A) 23
B) 22
C) 21
D) 1
D) 2

Question 32

A researcher wishes to determine the difference in two population means. To do this,she randomly samples 9 items from each population and computes a 90% confidence interval.The sample from the first population produces a mean of 780 with a standard deviation of 240.The sample from the second population produces a mean of 890 with a standard deviation of 280.Assume that the values are normally distributed in each population. The point estimate for the difference in the means of these two populations is _______.

A) -110
B) 40
C) -40
D) 0
E) 240

Question 33

The F statistic is a ratio of two independent sample variances.

Question 34

Golf course designer Roberto Langabeer is evaluating two sites,Palmetto Dunes and Ocean Greens,for his next golf course. He wants to prove that Palmetto Dunes residents (population 1)play golf more often than Ocean Greens residents (population 2). Roberto plans to test this hypothesis using a random sample of 81 individuals from each suburb.His null hypothesis is __________.

A) $\sigma$ ₁² < $\sigma$ ₂²
B) $\mu$ ₁- $\mu$ ₂ >0
C) p₁ - p₂ = 0
D) $\mu$ ₁ - $\mu$ ₂ = 0
E) s₁ - s₂ > 0

Question 35

Golf course designer Roberto Langabeer is evaluating two sites,Palmetto Dunes and Ocean Greens,for his next golf course. He wants to prove that Palmetto Dunes residents (population 1)play golf more often than Ocean Greens residents (population 2). Roberto commissions a market survey to test this hypothesis.The market researcher used a random sample of 64 individuals from each suburb,and reported the following: ₁ = 16 times per month and ₂ = 14 times per month.Assume that $\sigma$ ₁ = 4 and $\sigma$ ₂ = 3.With $\alpha$ = .01,the observed z value is _________________.

A) 18.29
B) 6.05
C) 5.12
D) 3.40
E) 3.20

Question 36

Golf course designer Roberto Langabeer is evaluating two sites,Palmetto Dunes and Ocean Greens,for his next golf course. He wants to prove that Palmetto Dunes residents (population 1)play golf more often than Ocean Greens residents (population 2). Roberto commissions a market survey to test this hypothesis.The market researcher used a random sample of 64 individuals from each suburb,and reported the following: ₁ = 15 times per month and ₂ = 14 times per month. Assume that $\sigma$ ₁ = 2 and $\sigma$ ₂ = 3. With $\alpha$ = .01,the appropriate decision is _________________.

A) reject the null hypothesis $\sigma$ ₁² < $\sigma$ ₂²
B) accept the alternate hypothesis $\mu$ ₁- $\mu$ ₂ >0
C) reject the alternate hypothesis n₁ = n₂ = 64
D) fail to reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ = 0
E) do nothing

Question 37

Golf course designer Roberto Langabeer is evaluating two sites,Palmetto Dunes and Ocean Greens,for his next golf course. He wants to prove that Palmetto Dunes residents (population 1)play golf more often than Ocean Greens residents (population 2). Roberto commissions a market survey to test this hypothesis.The market researcher used a random sample of 64 individuals from each suburb,and reported the following: ₁ = 15 times per month and ₂ = 14 times per month. Assume that $\sigma$ ₁ = 2 and $\sigma$ ₂ = 3. With $\alpha$ = .01,the observed z value is _________________.

A) 2.22
B) 12.81
C) 4.92
D) 3.58
E) 1.96

Question 38

Lucy Baker is analyzing demographic characteristics of two television programs,American Idol (population 1)and 60 Minutes (population 2). Previous studies indicate no difference in the ages of the two audiences. (The mean age of each audience is the same.) Lucy plans to test this hypothesis using a random sample of 100 from each audience. Her null hypothesis is ____________.

A) $\mu$ ₁ - $\mu$ ₂ $\neq$ 0
B) $\mu$ ₁ - $\mu$ ₂ > 0
C) $\mu$ ₁ - $\mu$ ₂ = 0
D) $\mu$ ₁ - $\mu$ ₂ < 0
E) $\mu$ ₁ - $\mu$ ₂ < 1

Question 39

A researcher wishes to determine the difference in two population means. To do this,she randomly samples 9 items from each population and computes a 90% confidence interval.The sample from the first population produces a mean of 780 with a standard deviation of 240.The sample from the second population produces a mean of 890 with a standard deviation of 280.Assume that the values are normally distributed in each population and that the population variances are approximately equal.The critical t value used from the table for this is _______.

A) 1.860
B) 1.734
C) 1.746
D) 1.337
E) 2.342

Question 40

The ratio of two independent sample variances follows the F distribution.

Question 41

A researcher wants to conduct a before/after study on 11 subjects to determine if a new cholesterol medication results in higher HDL cholesterol readings. The null hypothesis is that the average difference is zero while the alternative hypothesis is that the average difference is not zero. Scores are obtained on the subjects both before and after taking the medication.After subtracting the after scores from the before scores,the average difference is computed to be ?2.40 with a sample standard deviation of 1.21.Assume that the differences are normally distributed in the population. The degrees of freedom for this test are _______.

A) 11
B) 10
C) 9
D) 20
E) 2

Question 42

Maureen McIlvoy,owner and CEO of a mail order business for wind surfing equipment and supplies,is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years,neither warehouse has achieved the goal,but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1)and 400 orders from the East Coast Warehouse (population 2),and reports that 190 of the West Coast Orders were shipped within 24 hours,and the East Coast Warehouse shipped 356 orders within 24 hours. Assuming $\alpha$ = 0.05,the appropriate decision is ___________________.

A) reject the null hypothesis p₁ - p₂ = 0
B) reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ < 0
C) do not reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ = 0
D) do not reject the null hypothesis p₁ - p₂ = 0
E) do not reject the null hypothesis p₁ - p₂ ≥ 0

Question 43

A researcher is conducting a matched?pairs study.She gathers data on each pair in the study resulting in: Assume that the data are normally distributed in the population.The degrees of freedom in this problem are _______.

A) 4
B) 8
C) 5
D) 9
E) 3

Question 44

A researcher believes a new diet should improve weight gain.To test his hypothesis a random sample of 10 people on the old diet and an independent random sample of 10 people on the new diet were selected.The selected people on the old diet gain an average of 5 pounds with a standard deviation of 2 pounds,while the average gain for selected people on the new diet was 8 pounds with a standard deviation of 1.5 pounds.Assume that the values are normally distributed in each population and that the population variances are approximately equal.Using $\alpha$ = 0.05,the observed t value for this test is _______.

A) -1.96
B) -1.645
C) -2.100
D) -3.79
E) -1.734

Question 45

A researcher wants to conduct a before/after study on 11 subjects to determine if a new cholesterol medication results in higher HDL cholesterol readings. The null hypothesis is that the average difference is zero while the alternative hypothesis is that the average difference is not zero. Scores are obtained on the subjects both before and after taking the medication.After subtracting the after scores from the before scores,the average difference is computed to be ?2.40 with a sample standard deviation of 1.21.Assume that the differences are normally distributed in the population. The observed t value for this test is _______.

A) -21.82
B) -6.58
C) -2.4
D) 1.98
E) 2.33

Question 46

Maureen McIlvoy,owner and CEO of a mail order business for wind surfing equipment and supplies,is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years,neither warehouse has achieved the goal,but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1)and 400 orders from the East Coast Warehouse (population 2),and reports that 190 of the West Coast Orders were shipped within 24 hours,and the East Coast Warehouse shipped 372 orders within 24 hours. Maureen's alternative hypothesis is _______.

A) p₁ - p₂ $\neq$ 0
B) $\mu$ ₁ - $\mu$ ₂ > 0
C) p₁ - p₂ > 0
D) $\mu$ ₁ - $\mu$ ₂ $\neq$ 0
E) $\mu$ ₁ - $\mu$ ₂ ≥ 0

Question 47

A researcher is estimating the average difference between two population means based on matched?pairs samples.She gathers data on each pair in the study resulting in: Assume that the data are normally distributed in the population. A 95% confidence interval would be _______.

A) -3.02 to -0.18
B) -1.6 to -1.09
C) -2.11 to 1.09
D) -2.11 to -1.09
E) -3.23 to 2.23

Question 48

A researcher believes a new diet should improve weight gain.To test his hypothesis a random sample of 10 people on the old diet and an independent random sample of 10 people on the new diet were selected.The selected people on the old diet gain an average of 5 pounds with a standard deviation of 2 pounds,while the average gain for selected people on the new diet was 8 pounds with a standard deviation of 1.5 pounds.Assume that the values are normally distributed in each population and that the population variances are approximately equal.Using $\alpha$ = 0.05,the critical t value used from the table for this is _______.

A) -1.96
B) -1.645
C) -2.100
D) -3.79
E) -1.734

Question 49

A researcher wants to conduct a before/after study on 11 subjects to determine if a new cholesterol medication results in higher HDL cholesterol readings. The null hypothesis is that the average difference is zero while the alternative hypothesis is that the average difference is not zero. Scores are obtained on the subjects both before and after taking the medication.After subtracting the after scores from the before scores,the average difference is computed to be ?2.40 with a sample standard deviation of 1.21.A 0.05 level of significance is selected. Assume that the differences are normally distributed in the population. The table t value for this test is _______.

A) 1.812
B) 2.228
C) 2.086
D) 2.262
E) 3.2467

Question 50

A researcher is conducting a matched?pairs study.She gathers data on each pair in the study resulting in: Assume that the data are normally distributed in the population.The level of significance is selected to be 0.10. If the alternative hypothesis is that the average difference is greater than zero,the null hypothesis would be rejected if the observed value of t is _______.

A) greater than 1.533
B) less than -1.533
C) greater than 2.132
D) less than -2.132
E) equal to 2.333

Question 51

Suppose that .06 of each of two populations possess a given characteristic.Samples of size 400 are randomly drawn from each population.The probability that the difference between the first sample proportion which possess the given characteristic and the second sample proportion which possess the given characteristic being more than +.03 is _______.

A) 0.4943
B) 0.9943
C) 0.0367
D) 0.5057
E) 0.5700

Question 52

Maureen McIlvoy,owner and CEO of a mail order business for wind surfing equipment and supplies,is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years,neither warehouse has achieved the goal,but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1)and 400 orders from the East Coast Warehouse (population 2),and reports that 190 of the West Coast Orders were shipped within 24 hours,and the East Coast Warehouse shipped 372 orders within 24 hours. Assuming $\alpha$ = 0.05,the critical z value is ___________________.

A) -1.96
B) -1.64
C) 1.64
D) 1.96
E) 2.33

Question 53

Maureen McIlvoy,owner and CEO of a mail order business for wind surfing equipment and supplies,is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years,neither warehouse has achieved the goal,but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1)and 400 orders from the East Coast Warehouse (population 2),and reports that 190 of the West Coast Orders were shipped within 24 hours,and the East Coast Warehouse shipped 356 orders within 24 hours. Assuming $\alpha$ = 0.05,the observed z value is ___________________.

A) -3.15
B) 2.42
C) 1.53
D) 0.95
E) 1.05

Question 54

Maureen McIlvoy,owner and CEO of a mail order business for wind surfing equipment and supplies,is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years,neither warehouse has achieved the goal,but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1)and 400 orders from the East Coast Warehouse (population 2),and reports that 190 of the West Coast Orders were shipped within 24 hours,and the East Coast Warehouse shipped 372 orders within 24 hours. Assuming $\alpha$ = 0.05,the observed z value is ___________________.

A) -3.15
B) 2.42
C) 1.53
D) 0.95
E) 1.08

Question 55

A researcher is estimating the average difference between two population means based on matched?pairs samples.She gathers data on each pair in the study resulting in: Assume that the data are normally distributed in the population.To obtain a 90% confidence interval,the table t value would be _______.

A) 1.86
B) 1.397
C) 1.533
D) 2.132
E) 3.346

Question 56

A researcher is conducting a matched?pairs study.She gathers data on each pair in the study resulting in: Assume that the data are normally distributed in the population.The level of significance is selected to be 0.10. If a two-tailed test is performed,the null hypothesis would be rejected if the observed value of t is _______.

A) less than -1.533 or greater than 1.533
B) less than -2.132 or greater than 2.132
C) less than -2.776 or greater than 2.776
D) less than -1.860 or greater than 1.860
E) less than -2.000 or greater than 2.000

Question 57

A researcher is estimating the average difference between two population means based on matched?pairs samples.She gathers data on each pair in the study resulting in: Assume that the data are normally distributed in the population. To obtain a 95% confidence interval,the table t value would be _______.

A) 2.132
B) 1.86
C) 2.306
D) 2.976
E) 2.776

Question 58

Maureen McIlvoy,owner and CEO of a mail order business for wind surfing equipment and supplies,is reviewing the order filling operations at her warehouses.Her goal is 100% of orders shipped within 24 hours. In previous years,neither warehouse has achieved the goal,but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1)and 400 orders from the East Coast Warehouse (population 2),and reports that 190 of the West Coast Orders were shipped within 24 hours,and the East Coast Warehouse shipped 372 orders within 24 hours. Maureen's null hypothesis is ____.

A) p₁ - p₂ = 0
B) $\mu$ ₁ - $\mu$ ₂ = 0
C) p₁ - p₂ > 0
D) $\mu$ ₁ - $\mu$ ₂ < 0
E) $\mu$ ₁ - $\mu$ ₂ ≥ 0

Question 59

A researcher is conducting a matched?pairs study.She gathers data on each pair in the study resulting in: Assume that the data are normally distributed in the population.The sample standard deviation (s_d)of the differences is _______.

A) 1.3
B) 1.14
C) 1.04
D) 1.02
E) 1.47

Question 60

Maureen McIlvoy,owner and CEO of a mail order business for wind surfing equipment and supplies,is reviewing the order filling operations at her warehouses. Her goal is 100% of orders shipped within 24 hours. In previous years,neither warehouse has achieved the goal,but the East Coast Warehouse has consistently out-performed the West Coast Warehouse. Her staff randomly selected 200 orders from the West Coast Warehouse (population 1)and 400 orders from the East Coast Warehouse (population 2),and reports that 190 of the West Coast Orders were shipped within 24 hours,and the East Coast Warehouse shipped 372 orders within 24 hours. Assuming $\alpha$ = 0.05,the appropriate decision is ___________________.

A) do not reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ = 0
B) do not reject the null hypothesis p₁ - p₂ = 0
C) reject the null hypothesis $\mu$ ₁ - $\mu$ ₂ = 0
D) reject the null hypothesis p₁ - p₂ = 0
E) do not reject the null hypothesis p₁ - p₂ ≥ 0

Question 61

Tamara Hill,fund manager of the Hill Value Fund,manages a portfolio of 250 common stocks. Tamara is searching for a 'low risk' issue to add to the portfolio,i.e.,one with a price variance less than that of the S&P 500 index. Moreover,she assumes an issue is not 'low risk' until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1)was 25,and for the last seven quarters the price variance for XYC common (population 2)was 8. Assume that stock prices are normally distributed in the population.Using $\alpha$ = 0.05,the critical F value is _______.

A) 3.68
B) 3.58
C) 4.15
D) 3.29
E) 4.89

Question 62

Collinsville Construction Company purchases steel rods for its projects. Based on previous tests,Claude Carter,Quality Assurance Manager,has recommended purchasing rods from Redding Rods,Inc.(population 1),rather than Stockton Steel (population 2),since Redding's rods had less variability in length. Recently,Stockton revised it rod shearing operation,and Claude has sampled the outputs from Redding's and Stockton's rod manufacturing processes. The results for Redding were s₁² = 0.15 with n₁ = 8,and,for Stockton,the results were s₂² = 0.04 with n₂ = 10. Assume that rod lengths are normally distributed in the population If $\alpha$ = 0.05,the observed F value is ___________.

A) 0.27
B) 0.52
C) 1.92
D) 3.75
E) 4.25

Question 63

Collinsville Construction Company purchases steel rods for its projects. Based on previous tests,Claude Carter,Quality Assurance Manager,has recommended purchasing rods from Redding Rods,Inc.(population 1),rather than Stockton Steel (population 2),since Redding's rods had less variability in length. Recently,Stockton revised it rod shearing operation,and Claude has sampled the outputs from Redding's and Stockton's rod manufacturing processes. The results for Redding were s₁² = 0.10 with n₁ = 8,and,for Stockton,the results were s₂² = 0.05 with n₂ = 10. Assume that rod lengths are normally distributed in the population If $\alpha$ = 0.05,the appropriate decision is ________.

A) reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
B) reject the null hypothesis $\sigma$ ₁² $\neq$ $\sigma$ ₂²
C) do not reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
D) do not reject the null hypothesis $\sigma$ ₁² < $\sigma$ ₂²
E) do nothing

Question 64

Tamara Hill,fund manager of the Hill Value Fund,manages a portfolio of 250 common stocks. Tamara is searching for a 'low risk' issue to add to the portfolio,i.e.,one with a price variance less than that of the S&P 500 index. Moreover,she assumes an issue is not 'low risk' until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1)was 25,and for the last seven quarters the price variance for XYC common (population 2)was 8. Assume that stock prices are normally distributed in the population. Using $\alpha$ = 0.05,Tamara's alternate hypothesis is _______.

A) $\sigma$ ₁² = $\sigma$ ₂²
B) $\sigma$ ₁² $\neq$ $\sigma$ ₂²
C) $\sigma$ ₁² > $\sigma$ ₂²
D) $\sigma$ ₁² < $\sigma$ ₂²
E) s₁²< s₂²

Question 65

Collinsville Construction Company purchases steel rods for its projects. Based on previous tests,Claude Carter,Quality Assurance Manager,has recommended purchasing rods from Redding Rods,Inc.(population 1),rather than Stockton Steel (population 2),since Redding's rods had less variability in length. Recently,Stockton revised it rod shearing operation,and Claude has sampled the outputs from Redding's and Stockton's rod manufacturing processes. The results for Redding were s₁² = 0.10 with n₁ = 8,and,for Stockton,the results were s₂² = 0.05 with n₂ = 10. Assume that rod lengths are normally distributed in the population. Claude's null hypothesis is ________________.

A) $\sigma$ ₁²= $\sigma$ ₂²
B) $\sigma$ ₁² $\neq$$\sigma$ ₂²
C) $\sigma$ ₁² > $\sigma$ ₂²
D) $\sigma$ ₁² < $\sigma$ ₂²
E) s₁² < s₂²

Question 66

Tamara Hill,fund manager of the Hill Value Fund,manages a portfolio of 250 common stocks. Tamara is searching for a 'low risk' issue to add to the portfolio,i.e.,one with a price variance less than that of the S&P 500 index. Moreover,she assumes an issue is not 'low risk' until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1)was 25,and for the last seven quarters the price variance for XYC common (population 2)was 6. Assume that stock prices are normally distributed in the population.Using $\alpha$ = 0.05,the appropriate decision is _______.

A) reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
B) reject the null hypothesis $\sigma$ ₁² $\neq$ $\sigma$ ₂²
C) do not reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
D) do not reject the null hypothesis $\sigma$ ₁² $\neq$ $\sigma$ ₂²
E) maintain status quo

Question 67

Tamara Hill,fund manager of the Hill Value Fund,manages a portfolio of 250 common stocks. Tamara is searching for a 'low risk' issue to add to the portfolio,i.e.,one with a price variance less than that of the S&P 500 index. Moreover,she assumes an issue is not 'low risk' until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1)was 25,and for the last seven quarters the price variance for XYC common (population 2)was 8. Assume that stock prices are normally distributed in the population. Using $\alpha$ = 0.05,Tamara's null hypothesis is _______.

A) $\sigma$ ₁² = $\sigma$ ₂²
B) $\sigma$ ₁² $\neq$ $\sigma$ ₂²
C) $\sigma$ ₁² > $\sigma$ ₂²
D) $\sigma$ ₁² < $\sigma$ ₂²
E) s₁²< s₂²

Question 68

Suppose that .06 of each of two populations possess a given characteristic.Samples of size 400 are randomly drawn from each population.The standard deviation for the sampling distribution of differences between the first sample proportion and the second sample proportion (used to calculate the z score)is _______.

A) 0.00300
B) 0.01679
C) 0.05640
D) 0.00014
E) 0.12000

Question 69

Tamara Hill,fund manager of the Hill Value Fund,manages a portfolio of 250 common stocks. Tamara is searching for a 'low risk' issue to add to the portfolio,i.e.,one with a price variance less than that of the S&P 500 index. Moreover,she assumes an issue is not 'low risk' until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1)was 25,and for the last seven quarters the price variance for XYC common (population 2)was 8. Assume that stock prices are normally distributed in the population.Using $\alpha$ = 0.05,the appropriate decision is _______.

A) reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
B) reject the null hypothesis $\sigma$ ₁² $\neq$ $\sigma$ ₂²
C) do not reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
D) do not reject the null hypothesis $\sigma$ ₁² $\neq$ $\sigma$ ₂²
E) do nothing

Question 70

Collinsville Construction Company purchases steel rods for its projects. Based on previous tests,Claude Carter,Quality Assurance Manager,has recommended purchasing rods from Redding Rods,Inc.(population 1),rather than Stockton Steel (population 2),since Redding's rods had less variability in length. Recently,Stockton revised it rod shearing operation,and Claude has sampled the outputs from Redding's and Stockton's rod manufacturing processes. The results for Redding were s₁² = 0.10 with n₁ = 8,and,for Stockton,the results were s₂² = 0.05 with n₂ = 10. Assume that rod lengths are normally distributed in the population. If $\alpha$ = 0.05,the observed F value is ___________.

A) 0.50
B) 2.00
C) 1.41
D) 0.91
E) 0.71

Question 71

Tamara Hill,fund manager of the Hill Value Fund,manages a portfolio of 250 common stocks. Tamara is searching for a 'low risk' issue to add to the portfolio,i.e.,one with a price variance less than that of the S&P 500 index. Moreover,she assumes an issue is not 'low risk' until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1)was 25,and for the last seven quarters the price variance for XYC common (population 2)was 8. Assume that stock prices are normally distributed in the population.Using $\alpha$ = 0.05,the observed F value is _______.

A) 3.13
B) 0.32
C) 1.77
D) 9.77
E) 9.87

Question 72

Collinsville Construction Company purchases steel rods for its projects. Based on previous tests,Claude Carter,Quality Assurance Manager,has recommended purchasing rods from Redding Rods,Inc.(population 1),rather than Stockton Steel (population 2),since Redding's rods had less variability in length. Recently,Stockton revised it rod shearing operation,and Claude has sampled the outputs from Redding's and Stockton's rod manufacturing processes.The results for Redding were s₁² = 0.15 with n₁ = 8,and,for Stockton,the results were s₂² = 0.05 with n₂ = 10.Assume that rod lengths are normally distributed in the population.If $\alpha$ = 0.05,the appropriate decision is _________.

A) reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
B) reject the null hypothesis $\sigma$ ₁² < $\sigma$ ₂²
C) do not reject the null hypothesis $\sigma$ ₁² = $\sigma$ ₂²
D) do not reject the null hypothesis $\sigma$ ₁² < $\sigma$ ₂²
E) do nothing

Question 73

Tamara Hill,fund manager of the Hill Value Fund,manages a portfolio of 250 common stocks. Tamara is searching for a 'low risk' issue to add to the portfolio,i.e.,one with a price variance less than that of the S&P 500 index. Moreover,she assumes an issue is not 'low risk' until demonstrated otherwise. Her staff reported that during the last nine quarters the price variance for the S&P 500 index (population 1)was 25,and for the last seven quarters the price variance for XYC common (population 2)was 6. Assume that stock prices are normally distributed in the population.Using $\alpha$ = 0.05,the observed F value is _______.

A) 17.36
B) 2.04
C) 0.24
D) 4.77
E) 4.17

Question 74

A university administrator believes that business students are more likely to be working and going to school than their liberal arts majors.This information may lead to the business school offering courses in the evening hours while the liberal arts college maintains a daytime schedule. To test this theory the proportion of business students who are working at least 20 hours per week is compared to the proportion of liberal arts students who are working at least 20 hours per week..A random sample of 600 from the business school has been taken and it is determined that 480 students work at least 20 hours per week. A random sample of 700 liberal arts students showed that 350 work at least 20 hours per week. The observed z for this is _______.

A) 0.300
B) 0.624
C) 0.638
D) 11.22
E) 13.42

Question 75

A random sample of 400 items from a population shows that 160 of the sample items possess a given characteristic.A random sample of 400 items from a second population resulted in 110 of the sample items possessing the characteristic.Using this data,a 99% confidence interval is constructed to estimate the difference in population proportions which possess the given characteristic.The resulting confidence interval is _______.

A) 0.06 to 0.19
B) 0.05 to 0.22
C) 0.09 to 0.16
D) 0.04 to 0.21
E) 0.05 to 0.23

Question 76

Collinsville Construction Company purchases steel rods for its projects. Based on previous tests,Claude Carter,Quality Assurance Manager,has recommended purchasing rods from Redding Rods,Inc.(population 1),rather than Stockton Steel (population 2),since Redding's rods had less variability in length. Recently,Stockton revised it rod shearing operation,and Claude has sampled the outputs from Redding's and Stockton's rod manufacturing processes. The results for Redding were s₁² = 0.10 with n₁ = 8,and,for Stockton,the results were s₂² = 0.05 with n₂ = 10. Assume that rod lengths are normally distributed in the population.If $\alpha$ = 0.05,the critical F value is _____________.

A) 3.68
B) 3.29
C) 3.50
D) 3.79
E) 3.99

Question 77

Suppose that .06 of each of two populations possess a given characteristic.Samples of size 400 are randomly drawn from each population.What is the probability that the differences in sample proportions will be greater than 0.02?

A) 0.4535
B) 0.9535
C) 0.1170
D) 0.5465
E) 0.4650

Question 78

A researcher is interested in estimating the difference in two population proportions.A sample of 400 from each population results in sample proportions of .61 and .64. A 90% confidence interval for the difference in the population proportions is _______.

A) -0.10 to 0.04
B) -0.09 to 0.03
C) -0.11 to 0.05
D) -0.07 to 0.01
E) -0.08 to 0.12

Question 79

A researcher is interested in estimating the difference in two population proportions.A sample of 400 from each population results in sample proportions of .61 and .64.The point estimate of the difference in the population proportions is _______.

A) -0.030
B) 0.625
C) 0.000
D) 0.400
E) 0.500

Question 80

Collinsville Construction Company purchases steel rods for its projects. Based on previous tests,Claude Carter,Quality Assurance Manager,has recommended purchasing rods from Redding Rods,Inc.(population 1),rather than Stockton Steel (population 2),since Redding's rods had less variability in length. Recently,Stockton revised it rod shearing operation,and Claude has sampled the outputs from Redding's and Stockton's rod manufacturing processes. The results for Redding were s₁² = 0.10 with n₁ = 8,and,for Stockton,the results were s₂² = 0.05 with n₂ = 10. Assume that rod lengths are normally distributed in the population.Claude's alternative hypothesis is _____________.

A) $\sigma$ ₁² = $\sigma$ ₂²
B) $\sigma$ ₁² $\neq$ $\sigma$ ₂²
C) $\sigma$ ₁² > $\sigma$ ₂²
D) $\sigma$ ₁² < $\sigma$ ₂²
E) s₁² < s₂²