Deck 9: Hypothesis Testing

Question 1

As a general guideline, we use the alternative hypothesis as a vehicle to establish something new, or contest the status quo, for which a corrective action may be required.

Answer 1

True

Question 2

To obtain the p-value for a right-tailed test of the population mean, when σ is unknown, we use the Excel's function ________.

Answer 2

T.DIST.RT

Question 3

Under the assumption that the null hypothesis is true as an equality, the p-value is the likelihood of observing a sample mean that is at least as extreme as the one derived from the given sample.

Answer 3

True

Question 4

Given the ________ of the z distribution, the p-value for a two-tailed test is twice that of the p-value for a one-tailed test.

Question 5

For a given sample size, any attempt to reduce the likelihood of making one type of error (Type I or Type II) will increase the likelihood of the other error.

Question 6

On the basis of sample information, we either "accept the null hypothesis" or "reject the null hypothesis."

Question 7

Excel's function ________ returns the p-value for a right-tailed test of the population mean, when the raw data is available and is known.

Question 8

The hypothesis statement H: µ = 25 is an example of a(an) ________ hypothesis.

Question 9

If we reject a null hypothesis at the 1% significance level, then we have ________ evidence that the null hypothesis is false.

Question 10

The alternative hypothesis typically agrees with the status quo.

Question 11

A Type I error is committed when we reject the null hypothesis, which is actually true.

Question 12

In a one-tailed test, the rejection region is located under one tail (left or right) of the corresponding probability distribution, while in a two-tailed test this region is located under both tails.

Question 13

In general, the null and alternative hypotheses are ________.

A) additive
B) correlated
C) multiplicative
D) mutually exclusive

Question 14

A(n) ________ error is committed when we reject the null hypothesis when the null hypothesis is true.

Question 15

We define the allowed probability of making a Type I error as α, and we refer to 100α% as the ________.

Question 16

The hypothesis statement H: μ < 60 is an example of a(an) ________ hypothesis.

Question 17

A hypothesis test regarding the population mean µ is based on the sampling distribution of the sample mean .

Question 18

The null hypothesis in a hypothesis test refers to ________.

A) the desired outcome
B) the default state of nature
C) the altered state of nature
D) the desired state of nature

Question 19

A Type II error is made when we reject the null hypothesis and the null hypothesis is actually false.

Question 20

The null hypothesis typically corresponds to a presumed default state of nature.

Question 21

A Type I error occurs when we ________.

A) reject the null hypothesis when it is actually true
B) reject the null hypothesis when it is actually false
C) do not reject the null hypothesis when it is actually true
D) do not reject the null hypothesis when it is actually false

Question 22

A Type II error occurs when we ________.

A) reject the null hypothesis when it is actually true
B) reject the null hypothesis when it is actually false
C) do not reject the null hypothesis when it is actually true
D) do not reject the null hypothesis when it is actually false

Question 23

It is generally believed that no more than 0.50 of all babies in a town in Texas are born out of wedlock. A politician claims that the proportion of babies born out of wedlock is increasing. Identify the correct null and alternative hypotheses to test the politician's claim.

A) H₀: p = 0.50 and H_A: p ≠ 0.50
B) H₀: p ≤ 0.50 and H_A: p > 0.50
C) H₀: p ≥ 0.50 and H_A: p > 0.50
D) H₀: p ≥ 0.50 and H_A: p < 0.50

Question 24

For a given sample size n, ________.

A) decreasing the probability of a Type I error α will increase the probability of a Type II error β
B) decreasing the probability of a Type I error α will decrease the probability of a Type II error β
C) changing the probability of a Type I error α will have no impact on the probability of a Type II error β
D) increasing the probability of a Type I error α will increase the probability of a Type II error β as long as σ is known

Question 25

The alternative hypothesis typically ________.

A) corresponds to the presumed default state of nature
B) contests the status quo, for which a corrective action may be required
C) states the probability of rejecting the null hypothesis when it is false
D) states the probability of rejecting the null hypothesis when it is true

Question 26

It is generally believed that no more than 0.50 of all babies in a town in Texas are born out of wedlock. A politician claims that the proportion of babies born out of wedlock is increasing. When testing the two hypotheses, H₀: p ≤ 0.50 and H_A: p > 0.50, p stands for ________.

A) the current proportion of babies born out of wedlock
B) the mean number of babies born out of wedlock
C) the number of babies born out of wedlock
D) the general belief that the proportion of babies born out of wedlock is no more than 0.50

Question 27

It is generally believed that no more than 0.50 of all babies in a town in Texas are born out of wedlock. A politician claims that the proportion of babies born out of wedlock is increasing. In testing the politician's claim, how does one define the population parameter of interest?

A) The current proportion of babies born out of wedlock
B) The mean number of babies born out of wedlock
C) The number of babies born out of wedlock
D) The general belief that the proportion of babies born out of wedlock is no more than 0.50

Question 28

A professional sports organization is going to implement a test for steroids. The test gives a positive reaction in 94% of the people who have taken the steroid. However, it erroneously gives a positive reaction in 4% of the people who have not taken the steroid. What is the probability of Type I and Type II errors giving the null hypothesis "the individual has not taken steroids."

A) Type I: 4%, Type II: 6%
B) Type I: 6%, Type II: 4%
C) Type I: 94%, Type II: 4%
D) Type I: 4%, Type II: 94%

Question 29

A local courier service advertises that its average delivery time is less than 6 hours for local deliveries. When testing the two hypotheses, H₀: μ ≥ 6 and H_A: μ < 6, μ stand for ________.

A) the mean delivery time
B) the standard deviation of the delivery time
C) the number of deliveries that took less than 6 hours
D) the proportion of deliveries that took less than 6 hours

Question 30

Which of the following answers represents the objective of a hypothesis test?

A) Rejecting the null hypothesis when it is true.
B) Rejecting the null hypothesis when it is false.
C) Not rejecting the null hypothesis when it is true.
D) Rejecting the null hypothesis when it is false and not rejecting the null hypothesis when it is true.

Question 31

Consider the following hypotheses that relate to the medical field: H₀: A person is free of disease.
H_A: A person has disease.
In this instance, a Type II error is often referred to as ________.

A) a false positive
B) a false negative
C) a negative result
D) the power of the test

Question 32

When we reject the null hypothesis when it is actually false, we have committed ________.

A) no error
B) a Type I error
C) a Type II error
D) a Type I error and a Type II error

Question 33

A fast-food franchise is considering building a restaurant at a busy intersection. A financial advisor determines that the site is acceptable only if, on average, more than 300 automobiles pass the location per hour. If the advisor tests the hypotheses H₀: μ ≤ 300 versus H_A: μ > 300, μ stands for ________.

A) the average number of automobiles that pass the intersection per hour
B) the number of automobiles that pass the intersection per hour
C) the proportion of automobiles that pass the intersection per hour
D) the standard deviation of the number of automobiles that pass the intersection per hour

Question 34

A statistics professor works tirelessly to catch students cheating on his exams. He has particular routes for his teaching assistants to patrol, an elevated chair to ensure an unobstructed view of all students, and even a video recording of the exam in case additional evidence needs to be collected. He estimates that he catches 95% of students who cheat in his class, but 1% of the time that he accuses a student of cheating he is actually incorrect. Consider the null hypothesis, "the student is not cheating." What is the probability of a Type I error?

A) 1%
B) 5%
C) 95%
D) 99%

Question 35

A fast-food franchise is considering building a restaurant at a busy intersection. A financial advisor determines that the site is acceptable only if, on average, more than 300 automobiles pass the location per hour. The advisor tests the following hypotheses: H₀: μ ≤ 300.
H_A: μ > 300.
The consequences of committing a Type I error would be that ________.

A) the franchiser builds on an acceptable site
B) the franchiser builds on an unacceptable site
C) the franchiser does not build on an acceptable site
D) the franchiser does not build on an unacceptable site

Question 36

Which of the following types of tests may be performed?

A) Right-tailed and two-tailed tests
B) Left-tailed and two-tailed tests
C) Right-tailed and left-tailed tests
D) Right-tailed, left-tailed, and two-tailed tests

Question 37

Consider the following hypotheses that relate to the medical field: H₀: A person is free of disease.
H_A: A person has disease.
In this instance, a Type I error is often referred to as ________.

A) a false positive
B) a false negative
C) a negative result
D) the power of the test

Question 38

A fast-food franchise is considering building a restaurant at a busy intersection. A financial advisor determines that the site is acceptable only if, on average, more than 300 automobiles pass the location per hour. The advisor tests the following hypotheses: H₀: μ ≤ 300.
H_A: μ > 300.
The consequences of committing a Type II error would be that ________.

A) the franchiser builds on an acceptable site
B) the franchiser builds on an unacceptable site
C) the franchiser does not build on an acceptable site
D) the franchiser does not build on an unacceptable site

Question 39

The national average for an eighth-grade reading comprehension test is 73. A school district claims that its eighth-graders outperform the national average. In testing the school district's claim, how does one define the population parameter of interest?

A) The mean score on the eighth-grade reading comprehension test
B) The number of eighth graders who took the reading comprehension test
C) The standard deviation of the score on the eighth-grade reading comprehension test
D) The proportion of eighth graders who scored above 73 on the reading comprehension test

Question 40

Many cities around the United States are installing LED streetlights, in part to combat crime by improving visibility after dusk. An urban police department claims that the proportion of crimes committed after dusk will fall below the current level of 0.84 if LED streetlights are installed. Specify the null and alternative hypotheses to test the police department's claim.

A) H₀: p = 0.84 and H_A: p ≠ 0.84
B) H₀: p < 0.84 and H_A: p ≥ 0.84
C) H₀: p ≤ 0.84 and H_A: p > 0.84
D) H₀: p ≥ 0.84 and H_A: p < 0.84

Question 41

Which of the following represents an appropriate set of hypotheses?

A) H₀: = 0, H_A: ≠ 0
B) H₀: < 0, H_A: > 0
C) H₀: μ < 0, H_A: μ > 0
D) H₀: μ = 0, H_A: μ ≠ 0

Question 42

When conducting a hypothesis test for a given sample size, if the probability of a Type I error decreases, then the ________.

A) probability of Type II error decreases
B) probability of incorrectly rejecting the null hypothesis increases
C) probability of incorrectly not rejecting the null hypothesis increases
D) probability of incorrectly not rejecting the null hypothesis decreases

Question 43

If the p-value for a hypothesis test is 0.07 and the chosen level of significance is α = 0.05, then the correct conclusion is to ________.

A) reject the null hypothesis
B) not reject the null hypothesis
C) reject the null hypothesis if σ = 10
D) not reject the null hypothesis if σ = 10

Question 44

What is the decision rule when using the p-value approach to hypothesis testing?

A) Reject H₀ if the p-value > α.
B) Reject H₀ if the p-value < α.
C) Do not reject H₀ if the p-value < 1 - α.
D) Do not reject H₀ if the p-value > 1 - α.

Question 45

Which of the following are one-tailed tests?

A) H₀: μ ≤ 10, H_A: μ > 10
B) H₀: μ = 10, H_A: μ ≠ 10
C) H₀: μ ≥ 400, H_A: μ < 400
D) Both H₀: μ ≤ 10, H_A: μ > 10 and H₀: μ ≥ 400, H_A: μ < 400

Question 46

A university is interested in promoting graduates of its honors program by establishing that the mean GPA of these graduates exceeds 3.50. A sample of 36 honors students is taken and is found to have a mean GPA equal to 3.60. The population standard deviation is assumed to equal 0.40. At a 5% significance level, the decision is to ________.

A) reject H₀ we can conclude that the mean GPA is significantly greater than 3.50
B) reject H₀ we cannot conclude that the mean GPA is significantly greater than 3.50
C) not reject H₀ we can conclude that the mean GPA is significantly greater than 3.50
D) not reject H₀ we cannot conclude that the mean GPA is significantly greater than 3.50

Question 47

A university is interested in promoting graduates of its honors program by establishing that the mean GPA of these graduates exceeds 3.50. A sample of 36 honors students is taken and is found to have a mean GPA equal to 3.60. The population standard deviation is assumed to equal 0.40. To establish whether the mean GPA exceeds 3.50, the appropriate hypotheses are ________.

A) H₀: μ ≤ 3.50, H_A: μ > 3.50
B) H₀: ≤ 3.50, H_A: > 3.50
C) H₀: μ ≥ 3.50, H_A: μ < 3.50
D) H₀: ≥ 3.50, H_A: < 3.50

Question 48

If the null hypothesis is rejected at a 1% significance level, then ________.

A) the null hypothesis will be rejected at a 5% significance level
B) the alternative hypothesis will be rejected at a 5% significance level
C) the null hypothesis will not be rejected at a 5% significance level
D) the alternative hypothesis will not be rejected at a 5% significance level

Question 49

Which of the following are two-tailed tests?

A) H₀: μ ≤ 10, H_A: μ > 10
B) H₀: μ = 10, H_A: μ ≠ 10
C) H₀: μ ≥ 400, H_A: μ < 400
D) Both H₀: μ ≤ 10, H_A: μ > 10 and H₀: μ ≥ 400, H_A: μ < 400

Question 50

When conducting a hypothesis test for a given sample size, if α is increased from 0.05 to 0.10, then ________.

A) the probability of incorrectly rejecting the null hypothesis increases
B) the probability of incorrectly failing to reject the null hypothesis decreases
C) the probability of Type II error decreases
D) All of the above

Question 51

When conducting a hypothesis test concerning the population proportion, the value of the test statistic is calculated as ________.

A) z =
B) t_df =
C) z =
D) t_df =

Question 52

A university is interested in promoting graduates of its honors program by establishing that the mean GPA of these graduates exceeds 3.50. A sample of 36 honors students is taken and is found to have a mean GPA equal to 3.60. The population standard deviation is assumed to equal 0.40. The value of the test statistic is ________.

A) z = -1.50
B) t₃₅ = -1.50
C) z = 1.50
D) t₃₅ = 1.50

Question 53

If the p-value for a hypothesis test is 0.027 and the chosen level of significance is α = 0.05, then the correct conclusion is to ________.

A) reject the null hypothesis
B) not reject the null hypothesis
C) reject the null hypothesis if σ = 10
D) not reject the null hypothesis if σ = 10

Question 54

When conducting a hypothesis test concerning the population mean, and the population standard deviation is unknown, the value of the test statistic is calculated as ________.

A) z =
B) t_df =
C) z =
D) t_df =

Question 55

Consider the following competing hypotheses: H₀: μ = 0, H_A: μ ≠ 0. The value of the test statistic is z = −1.38. If we choose a 5% significance level, then we ________.

A) reject the null hypothesis and conclude that the population mean is significantly different from zero
B) reject the null hypothesis and conclude that the population mean is not significantly different from zero
C) do not reject the null hypothesis and conclude that the population mean is significantly different from zero
D) do not reject the null hypothesis and conclude that the population mean is not significantly different from zero

Question 56

A university is interested in promoting graduates of its honors program by establishing that the mean GPA of these graduates exceeds 3.50. A sample of 36 honors students is taken and is found to have a mean GPA equal to 3.60. The population standard deviation is assumed to equal 0.40. The parameter to be tested is ________.

A) the mean GPA of all university students
B) the mean GPA of the university honors students
C) the mean GPA of 3.60 for the 36 selected honors students
D) the proportion of honors students with a GPA exceeding 3.50

Question 57

When conducting a hypothesis test concerning the population mean, and the population standard deviation is known, the value of the test statistic is calculated as ________.

A) z =
B) t_df =
C) z =
D) t_df =

Question 58

When conducting a hypothesis test, which of the following decisions represents an error?

A) Rejecting the null hypothesis when it is true.
B) Rejecting the null hypothesis when it is false.
C) Not rejecting the null hypothesis when it is true.
D) Rejecting the null hypothesis when it is false and not rejecting the null hypothesis when it is true.

Question 59

A hypothesis test regarding the population mean is based on ________.

A) the sampling distribution of the sample mean
B) the sampling distribution of the sample variance
C) the sampling distribution of the sample proportion
D) the sampling distribution of the sample standard deviation

Question 60

If the chosen significance level is α = 0.05, then ________.

A) there is a 5% probability of rejecting a true null hypothesis
B) there is a 5% probability of accepting a true null hypothesis
C) there is a 5% probability of rejecting a false null hypothesis
D) there is a 5% probability of accepting a false null hypothesis

Question 61

The Boston public school district has had difficulty maintaining on-time bus service for its students ("A Year Later, School Buses Still Late," Boston Globe, October 5). Suppose the district develops a new bus schedule to help combat chronic lateness on a particularly woeful route. Historically, the bus service on the route has been, on average, 12 minutes late. After the schedule adjustment, the first 36 runs were an average of eight minutes late. As a result, the Boston public school district claimed that the schedule adjustment was an improvement-students were not as late. Assume a population standard deviation for bus arrival time of 12 minutes. The value of the test statistic is ________.

A) t₃₅ = -2.00
B) z = -2.00
C) t₃₅ = -0.33
D) z = -0.33

Question 62

A schoolteacher is worried that the concentration of dangerous, cancer-causing radon gas in her classroom is greater than the safe level of 4pCi/L. The school samples the air for 36 days and finds an average concentration of 4.4pCi/L with a standard deviation of 1pCi/L. The value of the test statistic is ________.

A) t₃₅ = -2.40
B) z = -2.40
C) t₃₅ = 2.40
D) z = 2.40

Question 63

A car dealer who sells only late-model luxury cars recently hired a new salesperson and believes that this salesperson is selling at lower markups. He knows that the long-run average markup in his lot is $5,600. He takes a random sample of 16 of the new salesperson's sales and finds an average markup of $5,000 and a standard deviation of $800. Assume the markups are normally distributed. What is the value of an appropriate test statistic for the car dealer to use to test his claim?

A) t₁₅ = -3.00
B) z = -3.00
C) t₁₅ = -0.75
D) z = -0.75

Question 64

A 99% confidence interval for the population mean yields the following results: [−3.79, 5.86]. At the 1% significance level, what decision should be made regarding the following hypothesis test with H₀: μ = 0, H_A: μ ≠ 0?

A) Reject H₀; we can conclude that the mean differs from zero.
B) Reject H₀; we cannot conclude that the mean differs from zero.
C) Do not reject H₀; we can conclude that the mean differs from zero.
D) Do not reject H₀; we cannot conclude that the mean differs from zero.

Question 65

A university interested in tracking its honors program believes that the proportion of graduates with a GPA of 3.00 or below is less than 0.20. In a sample of 200 graduates, 30 students have a GPA of 3.00 or below. In testing the university's belief, how does one define the population parameter of interest?

A) It's the proportion of honors graduates with a GPA of 3.00 or below.
B) It's the mean number of honors graduates with a GPA of 3.00 or below.
C) It's the number of honors graduates with a GPA of 3.00 or below.
D) It's the standard deviation of the number of honors graduates with a GPA of 3.00 or below.

Question 66

The Boston public school district has had difficulty maintaining on-time bus service for its students ("A Year Later, School Buses Still Late," Boston Globe, October 5). Suppose the district develops a new bus schedule to help combat chronic lateness on a particularly woeful route. Historically, the bus service on the route has been, on average, 12 minutes late. After the schedule adjustment, the first 36 runs were an average of eight minutes late. As a result, the Boston public school district claimed that the schedule adjustment was an improvement-students were not as late. Assume a population standard deviation for bus arrival time of 12 minutes. Which of the following can be used to determine whether the schedule adjustment reduced the average lateness time of 12 minutes?

A) H₀: μ = 8, H_A: μ ≠ 8
B) H₀: μ < 12, H_A: μ ≥ 12
C) H₀: μ ≥ 12, H_A: μ < 12
D) H₀: ≥ 8, H_A: < 8

Question 67

To test if the mean IQ of employees in an organization is greater than 100, a sample of 30 employees is taken and the value of the test statistic is computed as t₂₉ = 2.42 If we choose a 5% significance level, we ________.

A) reject the null hypothesis and conclude that the mean IQ is greater than 100
B) reject the null hypothesis and conclude that the mean IQ is not greater than 100
C) do not reject the null hypothesis and conclude that the mean IQ is greater than 100
D) do not reject the null hypothesis and conclude that the mean IQ is not greater than 100

Question 68

The owner of a large car dealership believes that the financial crisis decreased the number of customers visiting her dealership. The dealership has historically had 800 customers per day. The owner takes a sample of 100 days and finds the average number of customers visiting the dealership per day was 750. Assume that the population standard deviation is 350. At the 5% significance level, the decision is to ________.

A) reject H₀; we can conclude that the mean number of customers visiting the dealership is significantly less than 800
B) reject H₀; we cannot conclude that the mean number of customers visiting the dealership is significantly less than 800
C) do not reject H₀; we can conclude that the mean number of customers visiting the dealership is significantly less than 800
D) do not reject H₀; we cannot conclude that the mean number of customers visiting the dealership is significantly less than 800

Question 69

A university interested in tracking its honors program believes that the proportion of graduates with a GPA of 3.00 or below is less than 0.20. In a sample of 200 graduates, 30 students have a GPA of 3.00 or below. The value of the test statistic and its associated p-value are ________.

A) t₁₉₉ = -1.77 and p-value = 0.0385
B) z = -1.77 and p-value = 0.0385
C) t₁₉₉ = -1.77 and p-value = 0.0768
D) z = -1.77 and p-value = 0.0768

Question 70

A newly hired basketball coach promised a high-paced attack that will put more points on the board than the team's previously tepid offense historically managed. After a few months, the team owner looks at the data to test the coach's claim. He takes a sample of 36 of the team's games under the new coach and finds that they scored an average of 101 points with a standard deviation of 6 points. Over the past 10 years, the team had averaged 99 points. What is the value of the appropriate test statistic to test the new coach's claim at the 1% significance level?

A) t₃₅ = 0.33
B) z = 0.33
C) t₃₅ = 2.00
D) z = 2.00

Question 71

You want to test if more than 20% of homes in a neighborhood have recently been sold through a short sale, at a foreclosure auction, or by the bank following an unsuccessful foreclosure auction. You take a sample of 60 homes from this neighborhood and find that 14 fit your criteria. The appropriate null and alternative hypotheses are ________.

A) H₀: ≤ 0.23, H_A: > 0.23
B) H₀: = 0.23, H_A: ≠ 0.23
C) H₀: p ≤ 0.20, H_A: p > 0.20
D) H₀: p = 0.20, H_A: p ≠ 0.20

Question 72

A university interested in tracking its honors program believes that the proportion of graduates with a GPA of 3.00 or below is less than 0.20. In a sample of 200 graduates, 30 students have a GPA of 3.00 or below. In testing the university's belief, the appropriate hypotheses are ________.

A) H₀: p = 0.15, H_A: p ≠ 0.15
B) H₀: p ≤ 0.20, H_A: p > 0.20
C) H₀: > 0.15, H_A: < 0.15
D) H₀: p ≥ 0.20, H_A: p < 0.20

Question 73

The owner of a large car dealership believes that the financial crisis decreased the number of customers visiting her dealership. The dealership has historically had 800 customers per day. The owner takes a sample of 100 days and finds the average number of customers visiting the dealership per day was 750. Assume that the population standard deviation is 350.To determine whether there has been a decrease in the average number of customers visiting the dealership daily, the appropriate hypotheses are ________.

A) H₀: μ ≤ 800, H_A: μ > 800
B) H₀: ≤ 800, H_A: > 800
C) H₀: μ ≥ 800, H_A: μ < 800
D) H₀: ≥ 800, H_A: < 800

Question 74

A schoolteacher is worried that the concentration of dangerous, cancer-causing radon gas in her classroom is greater than the safe level of 4pCi/L. The school samples the air for 36 days and finds an average concentration of 4.4pCi/L with a standard deviation of 1pCi/L. At a 5% significance level, the decision is to ________.

A) reject H₀; we can conclude that the mean concentration of radon gas is greater than the safe level
B) reject H₀; we cannot conclude that the mean concentration of radon gas is greater than the safe level
C) not reject H₀; we can conclude that the mean concentration of radon gas is greater than the safe level
D) not reject H₀; we cannot conclude that the mean concentration of radon gas is greater than the safe level

Question 75

What type of data would necessitate using a hypothesis test of the population proportion rather than a test of the population mean?

A) Ratio
B) Interval
C) Qualitative
D) Quantitative

Question 76

A university interested in tracking its honors program believes that the proportion of graduates with a GPA of 3.00 or below is less than 0.20. In a sample of 200 graduates, 30 students have a GPA of 3.00 or below. At a 5% significance level, the decision is to ________.

A) reject H₀; we can conclude that the proportion of graduates with a GPA of 3.00 or below is significantly less than 0.20
B) reject H₀; we cannot conclude that the proportion of graduates with a GPA of 3.00 or below is significantly less than 0.20
C) not reject H₀; we can conclude that the proportion of graduates with a GPA of 3.00 or below is significantly less than 0.20
D) not reject H₀; we cannot conclude that the proportion of graduates with a GPA of 3.00 or below is significantly less than 0.20

Question 77

A schoolteacher is worried that the concentration of dangerous, cancer-causing radon gas in her classroom is greater than the safe level of 4pCi/L. The school samples the air for 36 days and finds an average concentration of 4.4pCi/L with a standard deviation of 1pCi/L. To test whether the average level of radon gas is greater than the safe level, the appropriate hypotheses are ________.

A) H₀: μ ≤ 4.0, H_A: μ > 4.0
B) H₀: μ = 4.0, H_A: μ ≠ 4.0
C) H₀: μ ≥ 4.4, H_A: μ < 4.4
D) H₀: = 4.4, H_A: X ≠ 4.4

Question 78

A recent report claimed that Americans are retiring later in life (U.S. News & World Report, August 17). An economist wishes to determine if the mean retirement age has increased from 62. To conduct the relevant test, she takes a random sample of 38 Americans who have recently retired and computes the value of the test statistic as t₃₇ = 1.92. With α = 0.05, she ________.

A) rejects the null hypothesis and concludes that the mean retirement age has increased
B) rejects the null hypothesis and concludes that the mean retirement age has not increased
C) does not reject the null hypothesis and does not conclude that the mean retirement age has changed
D) does not reject the null hypothesis and does not conclude that the mean retirement age has increased

Question 79

The owner of a large car dealership believes that the financial crisis decreased the number of customers visiting her dealership. The dealership has historically had 800 customers per day. The owner takes a sample of 100 days and finds the average number of customers visiting the dealership per day was 750. Assume that the population standard deviation is 350. The value of the test statistic is ________.

A) z = -1.429
B) t₉₉ = -1.429
C) z = 1.429
D) t₉₉ = 1.429

Question 80

The owner of a large car dealership believes that the financial crisis decreased the number of customers visiting her dealership. The dealership has historically had 800 customers per day. The owner takes a sample of 100 days and finds the average number of customers visiting the dealership per day was 750. Assume that the population standard deviation is 350. The population parameter to be tested is ________.

A) the average number of 750 customers per day
B) the proportion of customers visiting the dealership per day
C) the mean number of customers visiting the dealership per day
D) the standard deviation of the number of customers visiting the dealership per day