Exam 10: Introduction to Estimation

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. -How large a sample of federal employees in Nevada should be taken if we want to estimate with 98% confidence the mean salary to within $2,000.The population standard deviation is assumed to be $10,500.

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Question 61

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

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Question 62

When constructing confidence interval estimate of $\mu$ ,doubling the sample size n decreases the width of the interval by half.

(True/False)

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Question 63

The confidence level that is considered to be the standard amongst statisticians is ____________________%.

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Question 64

Draw the sampling distribution of two unbiased estimators for $\mu$ ,one of which is relatively efficient.

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Question 65

To estimate the mean of a normal population whose standard deviation is 6,with a bound on the error of estimation equal to 1.2 and confidence level 99% requires a sample size of at least:

(Multiple Choice)

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Question 66

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. -An engineer for an electric fencing company is interested in the mean length of wires being cut automatically by machine.The desired length of the wires is 12 feet.It is known that the standard deviation in the cutting length is 0.15 feet.Suppose the engineer decided to estimate the mean length to within 0.025 with 99% confidence.What sample size would be needed?

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Question 67

The population mean is a(n) but quantity.

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Question 68

In the formula $In the formula ,the subscript \alpha / 2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean.$ ,the subscript $\alpha$ / 2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean.

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Question 69

Time Spent Playing Computer Games Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. -{Time Spent Playing Computer Games Narrative} Determine the 95% confidence interval estimate of the population mean if the sample mean is changed to 5.0 hours.

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Question 70

A random sample of 10 university students was surveyed to determine the amount of time spent weekly at the library.The times are: 13,14,5,6,8,10,7,12,15,and 3.If the times are normally distributed with a standard deviation of 5.2 hours,estimate with 90% confidence the mean weekly time at the library by all university students.

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Question 71

An unbiased estimator is said to be consistent if the difference between the estimator and the parameter grows smaller as the sample size grows larger.

(True/False)

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Question 72

In developing an interval estimate for a population mean,the population standard deviation $\sigma$ was assumed to be 8.The interval estimate was 50.0 $\pm$ 2.50.Had $\sigma$ equaled 16,the interval estimate would be 100 $\pm$ 5.0.

(True/False)

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Question 73

A financial consultant wanted to determine the mean annual return on Bond funds.A random sample of 60 returns shows a mean of 12%.If the population standard deviation is assumed to be 4%,estimate with 95% confidence the mean annual return on all Bond funds.

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Question 74

To estimate with 95% confidence the mean of a normal population whose standard deviation is assumed to be 4 and the maximum allowable sampling error is assumed to be 1,requires a random sample of size 62.

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Question 75

Suppose an interval estimate for the population mean was 62.84 to 69.46.The population standard deviation was assumed to be 6.50,and a sample of 100 observations was used.The mean of the sample was:

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Question 76

The sample variance (where you divide by n -1)is an unbiased estimator of the population variance.

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Question 77

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. -{College Dean Narrative} What sample size should be used?

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Question 78

The width of a confidence interval estimate of the population mean increases when the:

(Multiple Choice)

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Question 79

The sample size needed to estimate a population mean to within 1 unit with 90% confidence given that the population standard deviation is 10 is 17.

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Question 80

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Exam 10: Introduction to Estimation

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

When constructing confidence interval estimate of μ\muμ ,doubling the sample size n decreases the width of the interval by half.

The confidence level that is considered to be the standard amongst statisticians is ____________________%.

Draw the sampling distribution of two unbiased estimators for μ\muμ ,one of which is relatively efficient.

To estimate the mean of a normal population whose standard deviation is 6,with a bound on the error of estimation equal to 1.2 and confidence level 99% requires a sample size of at least:

The population mean is a(n)____________________ but ____________________ quantity.

In the formula ,the subscript α\alphaα / 2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean.

An unbiased estimator is said to be consistent if the difference between the estimator and the parameter grows smaller as the sample size grows larger.

In developing an interval estimate for a population mean,the population standard deviation σ\sigmaσ was assumed to be 8.The interval estimate was 50.0 ±\pm± 2.50.Had σ\sigmaσ equaled 16,the interval estimate would be 100 ±\pm± 5.0.

A financial consultant wanted to determine the mean annual return on Bond funds.A random sample of 60 returns shows a mean of 12%.If the population standard deviation is assumed to be 4%,estimate with 95% confidence the mean annual return on all Bond funds.

To estimate with 95% confidence the mean of a normal population whose standard deviation is assumed to be 4 and the maximum allowable sampling error is assumed to be 1,requires a random sample of size 62.

Suppose an interval estimate for the population mean was 62.84 to 69.46.The population standard deviation was assumed to be 6.50,and a sample of 100 observations was used.The mean of the sample was:

The sample variance (where you divide by n -1)is an unbiased estimator of the population variance.

College Dean A college dean would like to estimate a population mean to within 40 units with 99% confidence given that the population standard deviation is 200. -{College Dean Narrative} What sample size should be used?

The width of a confidence interval estimate of the population mean increases when the:

The sample size needed to estimate a population mean to within 1 unit with 90% confidence given that the population standard deviation is 10 is 17.

What Is Statistics

Graphical Descriptive Techniques I

Graphical Descriptive Techniques II

A: Numerical Descriptive Techniques

B: Numerical Descriptive Techniques

C: Numerical Descriptive Techniques

Data Collection and Sampling

Probability

A: Random Variables and Discrete Probability Distributions

B: Random Variables and Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions

Introduction to Hypothesis Testing

Inference About a Population

Inference About Comparing Two Populations

Analysis of Variance

Chi-Squared Tests

A: Simple Linear Regression and Correlation

B: Simple Linear Regression and Correlation

Multiple Regression

Model Building

Nonparametric Statistics

Time-Series Analysis and Forecasting

Statistical Process Control

Decision Analysis

Conclusion

Filters

When constructing confidence interval estimate of $\mu$ ,doubling the sample size n decreases the width of the interval by half.

Draw the sampling distribution of two unbiased estimators for $\mu$ ,one of which is relatively efficient.

The population mean is a(n) but quantity.

In the formula $In the formula ,the subscript \alpha / 2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean.$ ,the subscript $\alpha$ / 2 refers to the area in the lower tail or upper tail of the sampling distribution of the sample mean.

In developing an interval estimate for a population mean,the population standard deviation $\sigma$ was assumed to be 8.The interval estimate was 50.0 $\pm$ 2.50.Had $\sigma$ equaled 16,the interval estimate would be 100 $\pm$ 5.0.