Deck 9: Estimating the Value of a Parameter Using Confidence Intervals

Question 1

Choose the one alternative that best completes the statement or answers the question.

Answer 1

A

Question 2

Choose the one alternative that best completes the statement or answers the question.
A confidence interval with a 95% level of confidence means that the parameter will be in the interval for 95 out of 100 samples of the same size.

Answer 2

True

Question 3

Write the word or phrase

Answer 3

A

Question 4

Construct and Interpret a Confidence Interval for a Pop Mean, Assuming that the Pop Std Dev is Known

Question 5

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Question 6

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Question 7

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Question 8

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Question 9

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Question 10

Choose the one alternative that best completes the statement or answers the question.

Question 11

Choose the one alternative that best completes the statement or answers the question.

Question 12

Construct and Interpret a Confidence Interval for a Pop Mean, Assuming that the Pop Std Dev is Known

Question 13

Choose the one alternative that best completes the statement or answers the question.

Question 14

Choose the one alternative that best completes the statement or answers the question.

Question 15

Explain the Role of Margin of Error in Constructing a Confidence Interval
A 90% confidence interval for the mean percentage of airline reservations being canceled on the day of the flight is (1.2%, 4.5%). What is the point estimator of the mean percentage of reservations that are canceled on the day of the flight

A) 2.85%
B) 1.65%
C) 2.25%
D) 3.3%

Question 16

Write the word or phrase that best completes each statement or answers the question.

Question 17

Choose the one alternative that best completes the statement or answers the question.
A confidence interval for a parameter is

A) An interval of numbers combined with the likelihood the interval contains the unknown parameter.
B) A point estimate plus a margin of error.
C) An interval of probabilities concerning a parameter.
D) A statement of believability of a statistical result.

Question 18

Explain the Role of Margin of Error in Constructing a Confidence Interval
Suppose a 95% confidence interval for turns out to be (130, 300). To make more useful inferences from the data, it is desired to reduce the width of the confidence interval. Which of the following will result in a reduced interval width

A) All of these.
B) Increase the sample size.
C) Decrease the confidence level.
D) Increase the sample size and decrease the confidence level.

Question 19

Choose the one alternative that best completes the statement or answers the question.

Question 20

Choose the one alternative that best completes the statement or answers the question.

Question 21

Choose the one alternative that best completes the statement or answers the question.
The cell phone conversations of a random sample of 50 students has a standard deviation of 9.7 minutes. Find the margin of error, E, using a 90% confidence interval.

A) 2.26
B) 0.32
C) 1.37
D) 1.23

Question 22

Choose the one alternative that best completes the statement or answers the question.
As the level of confidence increases the margin of error decreases.

Question 23

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error
As the level of confidence increases the number of item to be included in a sample will decrease when the error and the standard deviation are held constant.

Question 24

Choose the one alternative that best completes the statement or answers the question.
What statistical values does the margin of error depend upon

Question 25

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error

Question 26

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error

Question 27

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error

Question 28

State the Properties of Student s t-Distribution

Question 29

State the Properties of Student s t-Distribution
Which of the following is not a characteristic of Students t distribution

A) mean of 1
B) symmetric distribution
C) depends on degrees of freedom.
D) For large samples, the t and z distributions are nearly equivalent.

Question 30

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error
In order to set rates, an insurance company is trying to estimate the number of sick days that full time workers at a local bank take per year. A previous study indicated that the standard deviation was 2.5 days. a) How large a sample must be selected if the company wants to be 98% confident that the true mean differs from the sample mean by no more than 1 day b) Repeat part (a) using a 99% confidence interval. Which level of confidence requires a larger sample size Explain.

Question 31

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error
A doctor at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 98% confident that the true mean is within 2 ounces of the sample mean The standard deviation of the birth weights is known to be 8 ounces.

A) 87
B) 86
C) 10
D) 9

Question 32

State the Properties of Student s t-Distribution

Question 33

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error

Question 34

State the Properties of Student s t-Distribution
Every Student s t-distribution with n < N, n the number in the sample and N the number in the population, will be less peaked and have thinner tails.

Question 35

State the Properties of Student s t-Distribution

Question 36

Explain the Role of Margin of Error in Constructing a Confidence Interval
A certain confidence in interval is 8.15 < < 9.45. Find the sample mean x and the margin of error E.

Question 37

State the Properties of Student s t-Distribution

Question 38

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error
The principal at Riverside High School would like to estimate the mean length of time each day that it takes all the buses to arrive and unload the students. How large a sample is needed if the principal would like to assert with 90% confidence that the sample mean is off by, at most, 7 minutes. Assume = 14 minutes.

A) 11
B) 10
C) 12
D) 13

Question 39

Determine the Sample Size Necessary for Estimating the Population Mean within a Specified Margin of Error
A standardized test has a mean of 104 and a standard deviation of 16. We want to be 98% certain that we are within 4 points of the true mean. Determine the required sample size.

A) 87
B) 10
C) 191
D) 1

Question 40

Explain the Role of Margin of Error in Constructing a Confidence Interval
Suppose a 90% confidence interval for turns out to be (120, 280). Based on the interval, do you believe the average is equal to 300

A) No, and I am 90% sure of it.
B) Yes, and I am 90% sure of it.
C) Yes, and I am 100% sure of it.
D) No, and I am 100% sure of it.

Question 41

Provide an appropriate response.

Question 42

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Question 43

Determine t-values

Question 44

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Question 45

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Question 46

Determine t-values

Question 47

Determine t-values

Question 48

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Question 49

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Question 50

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Question 51

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Question 52

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Question 53

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Question 54

State the Properties of Student s t-Distribution

Question 55

Determine t-values

Question 56

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Question 57

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Question 58

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Question 59

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Question 60

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Question 63

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Question 64

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Question 65

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Question 66

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Question 67

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Question 68

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A private opinion poll is conducted for a politician to determine what proportion of the population favors adding more national parks. How large a sample is needed in order to be 99% confident that the sample proportion will not differ from the true proportion by more than 5%

A) 664
B) 543
C) 1327
D) 13

Question 69

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Question 70

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Question 71

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Question 72

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Question 73

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Question 74

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Question 75

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Question 76

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Question 77

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A pollster wishes to estimate the number of left-handed scientists. How large a sample is needed in order to be 99% confident that the sample proportion will not differ from the true proportion by more than 6% A previous study indicates that the proportion of left-handed scientists is 9%.

A) 151
B) 124
C) 166
D) 47

Question 78

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Question 79

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Question 80

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