Question 1

The value of F.01 with 9 numerator and 20 denominator degrees of freedom is

Accepted Answer

A)  2.39. 
B)  2.94. 
C)  2.91. 
D)  3.46. 
A)  2.39. 
B)  2.94. 
C)  2.91. 
D)  3.46.

Question 2

?Which of the following rejection rules is proper?

Accepted Answer

A)  ?Reject H0 if p-value ? F?. 
B)  ?Reject H0 if F ? F?/2. 
C)  ?Reject H0 if p-value ? ?/2. 
D)  ?Reject H0 if F ? F?. 
A)  ?Reject H0 if p-value ? F?. 
B)  ?Reject H0 if F ? F?/2. 
C)  ?Reject H0 if p-value ? ?/2. 
D)  ?Reject H0 if F ? F?.

Question 3

Which of the following has a chi-square distribution?

Accepted Answer

A)  (n - 1)s2/σ2. 
B)  (n - 1)σ/s. 
C)  (n - 1)s/σ. 
A)  (n - 1)s2/σ2. 
B)  (n - 1)σ/s. 
C)  (n - 1)s/σ.

Question 4

A lumber company has claimed that the standard deviation for the lengths of their six-foot boards is .4 inches or less.To test their claim, a random sample of 16 six-foot boards is selected; and it is determined that the variance of the sample is .3.Do the results of the sample support the company's claim? Use α = .1.

Accepted Answer

Since χ² = 28.125 > 2

Question 5

A sample of n observations is taken from a normal population.The appropriate chi-square distribution has

Accepted Answer

A)  n degrees of freedom. 
B)  n - 1 degrees of freedom. 
C)  n - 2 degrees of freedom. 
D)  n - 3 degrees of freedom. 
A)  n degrees of freedom. 
B)  n - 1 degrees of freedom. 
C)  n - 2 degrees of freedom. 
D)  n - 3 degrees of freedom.

Question 6

Consider the following hypothesis problem.
n = 23, s2 = 60, H0: σ2 ≥ 66, Ha: σ2 < 66
If the test is to be performed at the 5% level, what are the critical value(s) from the chi-square distribution?

Accepted Answer

Question 7

​Consider the following sample information from Population A and Population B. ​
​
Sample A
Sample B
N
24
16
S2
32
38
​​
We want to test the hypothesis that the population variances are equal.The test statistic for this problem equals

Accepted Answer

A)  ​.67. 
B)  .84. 
C)  ​1.19. 
D)  ​1.50. 
A)  ​.67. 
B)  .84. 
C)  ​1.19. 
D)  ​1.50.

Question 8

A sample of 51 observations yielded a sample standard deviation of 5.If we want to test H0: σ2 = 20, the test statistic is

Accepted Answer

A)  62.5. 
B)  12.5. 
C)  51.25. 
D)  50. 
A)  62.5. 
B)  12.5. 
C)  51.25. 
D)  50.

Question 9

The value of F.05 with 8 numerator and 19 denominator degrees of freedom is

Accepted Answer

A)  2.48. 
B)  2.58. 
C)  3.63. 
D)  2.96. 
A)  2.48. 
B)  2.58. 
C)  3.63. 
D)  2.96.

Question 10

​In practice, the most frequently encountered hypothesis test about a population variance is a

Accepted Answer

A)  ​one-tailed test, with rejection region in the lower tail. 
B)  ​one-tailed test, with rejection region in the upper tail. 
C)  ​two-tailed test, with equal-size rejection regions. 
D)  ​two-tailed test, with unequal-size rejection regions. 
A)  ​one-tailed test, with rejection region in the lower tail. 
B)  ​one-tailed test, with rejection region in the upper tail. 
C)  ​two-tailed test, with equal-size rejection regions. 
D)  ​two-tailed test, with unequal-size rejection regions.

Question 11

A company claims that the standard deviation in their delivery times is less than 5 days.A sample of 27 past customers was taken.The average delivery time in the sample was 14 days with a standard deviation of 4.5 days.At the 5% level of significance, test the company's claim.Use the critical value approach.

Accepted Answer

H₀: σ² ≥ 25 H_a: σ² < 2

Question 12

At α = .1, test to see if the population variances from which the following samples were drawn are equal.

Accepted Answer

Since F = 1.27 < 2.1

Question 13

​Consider the following hypothesis problem. n = 14
H0: σ2 a: σ2 > 410
​
​The null hypothesis is to be tested at the 5% level of significance.The critical value(s) from the chi-square distribution table is(are)

Accepted Answer

A)  22.362. 
B)  ​23.685. 
C)  ​5.009 and 24.736. 
D)  ​5.629 and 26.119. 
A)  22.362. 
B)  ​23.685. 
C)  ​5.009 and 24.736. 
D)  ​5.629 and 26.119.

Question 14

Student advisors are interested in determining if the variances of the scores of day students and night students are the same.The following samples are drawn:
Day
Night
n1 = 25
n2 = 31
s1 = 9.8
s2 = 14.7
​
Test the equality of the variances of the populations.Let α = .05.

Accepted Answer

Since F = 2.25 > 2.2

Question 15

A random sample of 31 sales charge showed a sample standard deviation of $50.What is the 90% confidence interval estimate of the population standard deviation?

Accepted Answer

The answer of A random sample of 31 sales charge...

Question 16

A sample of 60 items from population 1 has a sample variance of 12 while a sample of 50 items from population 2 has a sample variance of 15.If we want to test whether the variances of the two populations are equal, the test statistic will have a value of

Accepted Answer

A)  .8. 
B)  1.56. 
C)  1.5. 
D)  1.25. 
A)  .8. 
B)  1.56. 
C)  1.5. 
D)  1.25.

Question 17

The random variable for a chi-square distribution may assume

Accepted Answer

A)  any value between -1 to 1. 
B)  any value between -∞ to +∞. 
C)  any negative value. 
D)  any value greater than zero. 
A)  any value between -1 to 1. 
B)  any value between -∞ to +∞. 
C)  any negative value. 
D)  any value greater than zero.

Question 18

​Consider the following hypothesis problem. n = 14
H0: σ2 a: σ2 > 410
​
​The test statistic equals

Accepted Answer

A)  .63. 
B)  ​12.68. 
C)  ​13.33. 
D)  ​13.68. 
A)  .63. 
B)  ​12.68. 
C)  ​13.33. 
D)  ​13.68.

Question 19

A random sample of 21 checking accounts at a bank showed an average daily balance of $430 with a standard deviation of $50.
a.
Provide a 95% confidence interval estimate for the variance of the population of the checking accounts.
b.
Provide a 95% confidence interval estimate for the standard deviation of the population of the checking accounts.

Accepted Answer

​
a.
1463.

Question 20

The standard deviation of the ages of a sample of 16 executives from the northern states was 8.2 years; while the standard deviation of the ages of a sample of 25 executives from the southern states was 12.8 years.At α = .1, test to see if there is any difference between the variances of the ages of all the northern and all the southern executives.

Accepted Answer

​
Since F = 2.44 > 2

The value of F_.01 with 9 numerator and 20 denominator degrees of freedom is

?Which of the following rejection rules is proper?

Which of the following has a chi-square distribution?

A sample of n observations is taken from a normal population.The appropriate chi-square distribution has

Consider the following hypothesis problem. n = 23, s2 = 60, H₀: σ² ≥ 66, H_a: σ² < 66 If the test is to be performed at the 5% level, what are the critical value(s) from the chi-square distribution?

Consider the following sample information from Population A and Population B. Sample A Sample B N 24 16 S² 32 38 We want to test the hypothesis that the population variances are equal.The test statistic for this problem equals

A sample of 51 observations yielded a sample standard deviation of 5.If we want to test H₀: σ² = 20, the test statistic is

The value of F_.05 with 8 numerator and 19 denominator degrees of freedom is

In practice, the most frequently encountered hypothesis test about a population variance is a

At α = .1, test to see if the population variances from which the following samples were drawn are equal.

Consider the following hypothesis problem. n = 14 H₀: σ² < 410 S = 20 H_a: σ² > 410 The null hypothesis is to be tested at the 5% level of significance.The critical value(s) from the chi-square distribution table is(are)

Student advisors are interested in determining if the variances of the scores of day students and night students are the same.The following samples are drawn: Day Night n₁ = 25 n₂ = 31 s₁ = 9.8 s₂ = 14.7 Test the equality of the variances of the populations.Let α = .05.

A random sample of 31 sales charge showed a sample standard deviation of $50.What is the 90% confidence interval estimate of the population standard deviation?

A sample of 60 items from population 1 has a sample variance of 12 while a sample of 50 items from population 2 has a sample variance of 15.If we want to test whether the variances of the two populations are equal, the test statistic will have a value of

The random variable for a chi-square distribution may assume

Consider the following hypothesis problem. n = 14 H₀: σ² < 410 S = 20 H_a: σ² > 410 The test statistic equals

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Introduction to Probability

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Comparing Multiple Proportions, Tests of Independence and Goodness of Fit

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Exam 11: Inferences About Population Variances

The value of F.01 with 9 numerator and 20 denominator degrees of freedom is

?Which of the following rejection rules is proper?

Which of the following has a chi-square distribution?

A sample of n observations is taken from a normal population.The appropriate chi-square distribution has

Consider the following hypothesis problem. n = 23, s2 = 60, H0: σ2 ≥ 66, Ha: σ2 < 66 If the test is to be performed at the 5% level, what are the critical value(s) from the chi-square distribution?

​Consider the following sample information from Population A and Population B. ​ ​ Sample A Sample B N 24 16 S2 32 38 ​​ We want to test the hypothesis that the population variances are equal.The test statistic for this problem equals

A sample of 51 observations yielded a sample standard deviation of 5.If we want to test H0: σ2 = 20, the test statistic is

The value of F.05 with 8 numerator and 19 denominator degrees of freedom is

​In practice, the most frequently encountered hypothesis test about a population variance is a

At α = .1, test to see if the population variances from which the following samples were drawn are equal.

​Consider the following hypothesis problem. n = 14 H0: σ2 < 410 S = 20 Ha: σ2 > 410 ​ ​The null hypothesis is to be tested at the 5% level of significance.The critical value(s) from the chi-square distribution table is(are)

Student advisors are interested in determining if the variances of the scores of day students and night students are the same.The following samples are drawn: Day Night n1 = 25 n2 = 31 s1 = 9.8 s2 = 14.7 ​ Test the equality of the variances of the populations.Let α = .05.

A random sample of 31 sales charge showed a sample standard deviation of $50.What is the 90% confidence interval estimate of the population standard deviation?

A sample of 60 items from population 1 has a sample variance of 12 while a sample of 50 items from population 2 has a sample variance of 15.If we want to test whether the variances of the two populations are equal, the test statistic will have a value of

The random variable for a chi-square distribution may assume

​Consider the following hypothesis problem. n = 14 H0: σ2 < 410 S = 20 Ha: σ2 > 410 ​ ​The test statistic equals

Data and Statistics

Descriptive Statistics: Tabular and Graphical Displays

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Interval Estimation

Hypothesis Tests

Inference About Means and Proportions With Two Populations

Comparing Multiple Proportions, Tests of Independence and Goodness of Fit

Experimental Design and Analysis of Variance

Simple Linear Regression

Multiple Regression

Filters

The value of F_.01 with 9 numerator and 20 denominator degrees of freedom is

Consider the following hypothesis problem. n = 23, s2 = 60, H₀: σ² ≥ 66, H_a: σ² < 66 If the test is to be performed at the 5% level, what are the critical value(s) from the chi-square distribution?

Consider the following sample information from Population A and Population B. Sample A Sample B N 24 16 S² 32 38 We want to test the hypothesis that the population variances are equal.The test statistic for this problem equals

A sample of 51 observations yielded a sample standard deviation of 5.If we want to test H₀: σ² = 20, the test statistic is

The value of F_.05 with 8 numerator and 19 denominator degrees of freedom is

In practice, the most frequently encountered hypothesis test about a population variance is a

Consider the following hypothesis problem. n = 14 H₀: σ² < 410 S = 20 H_a: σ² > 410 The null hypothesis is to be tested at the 5% level of significance.The critical value(s) from the chi-square distribution table is(are)

Student advisors are interested in determining if the variances of the scores of day students and night students are the same.The following samples are drawn: Day Night n₁ = 25 n₂ = 31 s₁ = 9.8 s₂ = 14.7 Test the equality of the variances of the populations.Let α = .05.

Consider the following hypothesis problem. n = 14 H₀: σ² < 410 S = 20 H_a: σ² > 410 The test statistic equals