Question 1

A point estimate is a range of values used to estimate a population parameter.

Accepted Answer

A) True 
 B)False  False

Question 2

A bank wishes to estimate the mean credit card balance owed by its customers. The population standard deviation is estimated to be $300. If a 98% confidence interval is used and an interval of $75 is desired, how many customers should be sampled?

Accepted Answer

A)  44 
B)  212 
C)  629 
D)  87 
A)  44 
B)  212 
C)  629 
D)  87 D

Question 3

A local health care company wants to estimate the mean weekly elder day-care cost. A sample of 10 facilities shows a mean of $250 per week, with a standard deviation of $25. What is the 90% confidence interval for the population mean?

Accepted Answer

[235.5089, 264.4911]
Explanation: We do not know the population standard deviation; hence, we use the sample standard deviation and the t distribution. To find the confidence interval, we use   .

Question 4

For a distribution of sample means with a known population standard deviation, about _____ percent of the sample means are within one standard error of population mean.

Accepted Answer

The answer of For a distribution of sample means with...

Question 5

A student wanted to construct a 95% confidence interval for the mean age of students in her statistics class. She randomly selected nine students. Their average age was 19.1 years with a sample standard deviation of 1.5 years. What is the best point estimate for the population mean?

Accepted Answer

A)  2.1 years 
B)  1.5 years 
C)  19.1 years 
D)  9 years 
A)  2.1 years 
B)  1.5 years 
C)  19.1 years 
D)  9 years

Question 6

A 95% confidence interval implies that about 95 out of 100 similarly constructed intervals will include the _____________ being estimated.

Accepted Answer

population

Question 7

A confidence interval for a population mean __________.

Accepted Answer

A)  estimates the population range 
B)  estimates a likely interval for a population mean 
C)  estimates likelihood or probability 
D)  estimates the population standard deviation 
A)  estimates the population range 
B)  estimates a likely interval for a population mean 
C)  estimates likelihood or probability 
D)  estimates the population standard deviation

Question 8

University officials say that at least 70% of the voting student population supports a fee increase. If the 95% confidence interval estimating the proportion of students supporting the fee increase is [0.75, 0.85], what conclusion can be drawn?

Accepted Answer

A)  Seventy percent is not in the interval, so another sample is needed. 
B)  Seventy percent is not in the interval, so assume it will not be supported. 
C)  The interval estimate is above 70%, so infer that it will be supported. 
D)  Since this was not based on the population, no conclusion can be drawn. 
A)  Seventy percent is not in the interval, so another sample is needed. 
B)  Seventy percent is not in the interval, so assume it will not be supported. 
C)  The interval estimate is above 70%, so infer that it will be supported. 
D)  Since this was not based on the population, no conclusion can be drawn.

Question 9

A survey of an urban university (population of 25,450) showed that 870 of 1,100 students sampled supported a fee increase to fund improvements to the student recreation center. Using the 99% level of confidence, what is the confidence interval for the proportion of students supporting the fee increase?

Accepted Answer

A)  [0.751, 0.829] 
B)  [0.759, 0.823] 
C)  [0.767, 0.814] 
D)  [0.771, 0.811] 
A)  [0.751, 0.829] 
B)  [0.759, 0.823] 
C)  [0.767, 0.814] 
D)  [0.771, 0.811]

Question 10

The estimate of the population proportion is to be within plus or minus .10, with a 95% level of confidence. The best estimate of the population proportion is .25. How large a sample is required?

Accepted Answer

73
Explanation: We use @#IMG-DLM& When c

Question 11

Sugar is packaged in 16-ounce bags. To test the weight of the bags, a few were checked. The mean weight was 15.95 ounces and the standard deviation was 0.5 ounces. How many bags must the processor sample to be 99% confident that the sample mean does not differ from the population mean by more than 0.2 ounces?

Accepted Answer

42
Explanation: We use @#IMG-DLM& When c

Question 12

As the sample size for a t distribution increases, the differences between the t distribution and the standard normal distribution:

Accepted Answer

A)  are unchanged and remain the same. 
B)  become smaller, as the t distribution approaches the standard normal distribution. 
C)  become greater. 
D)  are evident because the tails of the t distribution become thicker. 
A)  are unchanged and remain the same. 
B)  become smaller, as the t distribution approaches the standard normal distribution. 
C)  become greater. 
D)  are evident because the tails of the t distribution become thicker.

Question 13

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the 95% confidence interval for the proportion defective?

Accepted Answer

[0.0253, 0.0747]
Exp

Question 14

A survey of 16 executives showed a mean work time per week of 50 hours, with a standard deviation of 10 hours. What is the 95% confidence interval for the population mean?

Accepted Answer

[44.6725, 55.3275]
Explanation

Question 15

A random sample of 42 college graduates revealed that they worked an average of 5.5 years on the job before being promoted. The sample standard deviation was 1.1 years. Using the 0.99 degree of confidence, what is the confidence interval for the population mean?

Accepted Answer

A)  5.04 and 5.96 
B)  5.06 and 5.94 
C)  2.67 and 8.33 
D)  4.40 and 6.60 
A)  5.04 and 5.96 
B)  5.06 and 5.94 
C)  2.67 and 8.33 
D)  4.40 and 6.60

Question 16

A z statistic is used for a problem involving any sample size and an unknown population standard deviation.

Accepted Answer

A) True 
 B)False

Question 17

The finite population correction factor is applied when the population size is known.

Accepted Answer

A) True 
 B)False

Question 18

A sample of 100 students is selected from a known population of 1000 students to construct a 95% confidence interval for the average SAT score. What correction factor should be used to compute the standard error?

Accepted Answer

A)  0.949 
B)  0.901 
C)  1.96 
D)  Cannot be determined 
A)  0.949 
B)  0.901 
C)  1.96 
D)  Cannot be determined

Question 19

The Nile Superstore is conducting a survey of consumer preferences for a new wireless e-book reader. A sample of 160 people reveals that 120 would buy the new reader. What is the 99% confidence interval for the population proportion?

Accepted Answer

[0.6618, 0.8382]
Exp

Question 20

Knowing the population standard deviation, a 95% confidence interval infers that the population mean ___________.

Accepted Answer

A)  is between 0 and 100% 
B)  is within ±1.96 standard deviations of the sample mean 
C)  is within ±1.96 standard errors of the sample mean 
D)  is too large 
A)  is between 0 and 100% 
B)  is within ±1.96 standard deviations of the sample mean 
C)  is within ±1.96 standard errors of the sample mean 
D)  is too large

A point estimate is a range of values used to estimate a population parameter.

A bank wishes to estimate the mean credit card balance owed by its customers. The population standard deviation is estimated to be $300. If a 98% confidence interval is used and an interval of $75 is desired, how many customers should be sampled?

A local health care company wants to estimate the mean weekly elder day-care cost. A sample of 10 facilities shows a mean of $250 per week, with a standard deviation of $25. What is the 90% confidence interval for the population mean?

For a distribution of sample means with a known population standard deviation, about _____ percent of the sample means are within one standard error of population mean.

A student wanted to construct a 95% confidence interval for the mean age of students in her statistics class. She randomly selected nine students. Their average age was 19.1 years with a sample standard deviation of 1.5 years. What is the best point estimate for the population mean?

A 95% confidence interval implies that about 95 out of 100 similarly constructed intervals will include the _____________ being estimated.

A confidence interval for a population mean __________.

University officials say that at least 70% of the voting student population supports a fee increase. If the 95% confidence interval estimating the proportion of students supporting the fee increase is [0.75, 0.85], what conclusion can be drawn?

The estimate of the population proportion is to be within plus or minus .10, with a 95% level of confidence. The best estimate of the population proportion is .25. How large a sample is required?

As the sample size for a t distribution increases, the differences between the t distribution and the standard normal distribution:

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the 95% confidence interval for the proportion defective?

A survey of 16 executives showed a mean work time per week of 50 hours, with a standard deviation of 10 hours. What is the 95% confidence interval for the population mean?

A random sample of 42 college graduates revealed that they worked an average of 5.5 years on the job before being promoted. The sample standard deviation was 1.1 years. Using the 0.99 degree of confidence, what is the confidence interval for the population mean?

A z statistic is used for a problem involving any sample size and an unknown population standard deviation.

The finite population correction factor is applied when the population size is known.

A sample of 100 students is selected from a known population of 1000 students to construct a 95% confidence interval for the average SAT score. What correction factor should be used to compute the standard error?

The Nile Superstore is conducting a survey of consumer preferences for a new wireless e-book reader. A sample of 160 people reveals that 120 would buy the new reader. What is the 99% confidence interval for the population proportion?

Knowing the population standard deviation, a 95% confidence interval infers that the population mean ___________.

What Is Statistics

Describing Data: Frequency Tables, Frequency Distributions, and Graphic Presentation

Describing Data: Numerical Measures

Describing Data: Displaying and Exploring Data

A Survey of Probability Concepts

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Methods and the Central Limit Theorem

One-Sample Tests of Hypothesis

Two-Sample Tests of Hypothesis

Analysis of Variance

Correlation and Linear Regression

Multiple Regression Analysis

Nonparametric Methods: Nominal Level Hypothesis Tests

Nonparametric Methods: Analysis of Ordinal Data

Index Numbers

Time Series and Forecasting

Statistical Process Control and Quality Management

An Introduction to Decision Theory

Filters

Exam 9: Estimation and Confidence Intervals

A point estimate is a range of values used to estimate a population parameter.

A bank wishes to estimate the mean credit card balance owed by its customers. The population standard deviation is estimated to be $300. If a 98% confidence interval is used and an interval of $75 is desired, how many customers should be sampled?

A local health care company wants to estimate the mean weekly elder day-care cost. A sample of 10 facilities shows a mean of $250 per week, with a standard deviation of $25. What is the 90% confidence interval for the population mean?

For a distribution of sample means with a known population standard deviation, about _____ percent of the sample means are within one standard error of population mean.

A student wanted to construct a 95% confidence interval for the mean age of students in her statistics class. She randomly selected nine students. Their average age was 19.1 years with a sample standard deviation of 1.5 years. What is the best point estimate for the population mean?

A 95% confidence interval implies that about 95 out of 100 similarly constructed intervals will include the _____________ being estimated.

A confidence interval for a population mean __________.

University officials say that at least 70% of the voting student population supports a fee increase. If the 95% confidence interval estimating the proportion of students supporting the fee increase is [0.75, 0.85], what conclusion can be drawn?

The estimate of the population proportion is to be within plus or minus .10, with a 95% level of confidence. The best estimate of the population proportion is .25. How large a sample is required?

As the sample size for a t distribution increases, the differences between the t distribution and the standard normal distribution:

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the 95% confidence interval for the proportion defective?

A survey of 16 executives showed a mean work time per week of 50 hours, with a standard deviation of 10 hours. What is the 95% confidence interval for the population mean?

A random sample of 42 college graduates revealed that they worked an average of 5.5 years on the job before being promoted. The sample standard deviation was 1.1 years. Using the 0.99 degree of confidence, what is the confidence interval for the population mean?

A z statistic is used for a problem involving any sample size and an unknown population standard deviation.

The finite population correction factor is applied when the population size is known.

A sample of 100 students is selected from a known population of 1000 students to construct a 95% confidence interval for the average SAT score. What correction factor should be used to compute the standard error?

The Nile Superstore is conducting a survey of consumer preferences for a new wireless e-book reader. A sample of 160 people reveals that 120 would buy the new reader. What is the 99% confidence interval for the population proportion?

Knowing the population standard deviation, a 95% confidence interval infers that the population mean ___________.

What Is Statistics

Describing Data: Frequency Tables, Frequency Distributions, and Graphic Presentation

Describing Data: Numerical Measures

Describing Data: Displaying and Exploring Data

A Survey of Probability Concepts

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Methods and the Central Limit Theorem

One-Sample Tests of Hypothesis

Two-Sample Tests of Hypothesis

Analysis of Variance

Correlation and Linear Regression

Multiple Regression Analysis

Nonparametric Methods: Nominal Level Hypothesis Tests

Nonparametric Methods: Analysis of Ordinal Data

Index Numbers

Time Series and Forecasting

Statistical Process Control and Quality Management

An Introduction to Decision Theory

Filters