Question 1

What is the probability of a t-value smaller than 1.00?

Accepted Answer

The answer of What is the probability of a t-value...

Question 2

If the odds of a horse winning a race are 2 to 1,then the probability of this horse winning the race is_____.

Accepted Answer

A) 1/4 
B) 1/3 
C) 1/2 
D) 2/3 
E) None of the above 
A) 1/4 
B) 1/3 
C) 1/2 
D) 2/3 
E) None of the above

Question 3

You have been assigned to determine whether more people prefer Coke to Pepsi.Assume that roughly half the population prefers Coke and half prefers Pepsi.How large a sample would you need to take to ensure that you could estimate,with 95% confidence,the proportion of people preferring Coke within 3% of the actual value?

Accepted Answer

@#IMG-DLM& = 0.50,z - multiple

Question 4

In general,increasing the confidence level will narrow the confidence interval,and decreasing the confidence level widens the interval.

Accepted Answer

A) True 
 B)False

Question 5

(A)Construct a 95% confidence interval for   .
(B)Based on your answer to (A),are you convinced that the gaskets from shift 2 are,on average,wider than those from shift 1? Why or why not?

Accepted Answer

(A) @#IMG-DLM& @#IMG-DLM& The pooled standard deviation is @#IMG-DLM&

Question 6

The standard error of the sampling distribution of the sample proportion   ,when the sample size n = 50 and the population proportion p = 0.25,is 0.00375.

Accepted Answer

A) True 
 B)False

Question 7

The chi-square distribution for developing a confidence interval for a standard deviation has_____ degrees of freedom.

Accepted Answer

A) n + 2 
B) n +1 
C) n 
D) n - 1 
E) n - 2 
A) n + 2 
B) n +1 
C) n 
D) n - 1 
E) n - 2

Question 8

A 90% confidence interval estimate for a population mean   is determined to be 72.8 to 79.6.If the confidence level is reduced to 80%,the confidence interval for   becomes narrower.

Accepted Answer

A) True 
 B)False

Question 9

When the samples we want to compare are paired in some natural way,such as pretest/posttest for each person or husband/wife pairs,a more appropriate form of analysis is to not compare two separate variables,but their _____.

Accepted Answer

A) difference 
B) sum 
C) ratio 
D) total 
E) product 
A) difference 
B) sum 
C) ratio 
D) total 
E) product

Question 10

From a sample of 500 items,30 were found to be defective.The point estimate of the population proportion defective will be:

Accepted Answer

A) 0.06 
B) 30.0 
C) 16.667 
D) None of the above 
A) 0.06 
B) 30.0 
C) 16.667 
D) None of the above

Question 11

The interval estimate 18.5   2.5 was developed for a population mean when the sample standard deviation s was 7.5.Had s equaled 15,the interval estimate would be 37   5.0.

Accepted Answer

A) True 
 B)False

Question 12

After calculating the sample size needed to estimate a population proportion to within 0.05,you have been told that the maximum allowable error (B)must be reduced to just 0.025.If the original calculation led to a sample size of 1000,the sample size will now have to be:

Accepted Answer

A) 2000 
B) 4000 
C) 1000 
D) 8000 
A) 2000 
B) 4000 
C) 1000 
D) 8000

Question 13

Two independent samples of sizes 50 and 50 are randomly selected from two populations to test the difference between the population means,   .The sampling distribution of the sample mean difference   is:

Accepted Answer

A) normally distributed 
B) approximately normal 
C) t - distributed with 98 degrees of freedom 
D) chi-squared distributed with 99 degrees of freedom 
A) normally distributed 
B) approximately normal 
C) t - distributed with 98 degrees of freedom 
D) chi-squared distributed with 99 degrees of freedom

Question 14

In developing a confidence interval for the population standard deviation   ,we make use of the fact that the sampling distribution of the sample standard deviation s is not the normal distribution or the t-distribution,but rather a right-skewed distribution called the chi-square distribution,which (for this procedure)has n - 1 degrees of freedom.

Accepted Answer

A) True 
 B)False

Question 15

The t-distribution for developing a confidence interval for a mean has _____ degrees of freedom.

Accepted Answer

A) n + 2 
B) n +1 
C) n 
D) n - 1 
E) n - 2 
A) n + 2 
B) n +1 
C) n 
D) n - 1 
E) n - 2

Question 16

(A)Compute   has a t-distribution with 15 degrees of freedom.
(B)Compute   has a t-distribution with 150 degrees of freedom.
(C)How do you explain the difference between the results obtained in (A)and (B)?
(D)Compute   where Z is a standard normal random variable.
(E)Compare the results of (D)to the results obtained in (A)and (B).How do you explain the difference in these probabilities?

Accepted Answer

(A)By using the Excel function = TDIST (

Question 17

(A)Use a t - value of 2.014 to calculate a 95% confidence interval for the difference between the average female purchase and the average male purchase.Would you conclude that there is a significant difference between females and males in this case? Explain.
(B)What are the degrees of freedom for the t-multiple in this calculation? Explain how you would calculate the degrees of freedom in this case.
(C)What is the assumption in this case that allows you to use the pooled standard deviation for this confidence interval?

Accepted Answer

(A) @#IMG-DLM& 15.77±46.785 = (-31.015,62.555).Sin

Question 18

In past years,approximately 25% of all U.S.families purchased potato chips at least once a month.We are interested in determining the fraction of all U.S.families that currently purchase potato chips at least once a month.How many families must we survey if we want to be 99% sure that our estimate of the fraction of U.S.families currently purchasing potato chips at least once a month is accurate within 2%?

Accepted Answer

@#IMG-DLM& = 0.25,z

Question 19

If the standard error of the sampling distribution of the sample proportion   is 0.0324 for samples of size 200,then the population proportion must be 0.30.

Accepted Answer

A) True 
 B)False

Question 20

As the sample size increases,the t-distribution becomes more similar to the ________ distribution.

Accepted Answer

A) normal 
B) exponential 
C) multinominal 
D) chi-square 
E) binomial 
A) normal 
B) exponential 
C) multinominal 
D) chi-square 
E) binomial

What is the probability of a t-value smaller than 1.00?

If the odds of a horse winning a race are 2 to 1,then the probability of this horse winning the race is_____.

In general,increasing the confidence level will narrow the confidence interval,and decreasing the confidence level widens the interval.

(A)Construct a 95% confidence interval for . (B)Based on your answer to (A),are you convinced that the gaskets from shift 2 are,on average,wider than those from shift 1? Why or why not?

The standard error of the sampling distribution of the sample proportion ,when the sample size n = 50 and the population proportion p = 0.25,is 0.00375.

The chi-square distribution for developing a confidence interval for a standard deviation has_____ degrees of freedom.

A 90% confidence interval estimate for a population mean is determined to be 72.8 to 79.6.If the confidence level is reduced to 80%,the confidence interval for becomes narrower.

When the samples we want to compare are paired in some natural way,such as pretest/posttest for each person or husband/wife pairs,a more appropriate form of analysis is to not compare two separate variables,but their _____.

From a sample of 500 items,30 were found to be defective.The point estimate of the population proportion defective will be:

The interval estimate 18.5 2.5 was developed for a population mean when the sample standard deviation s was 7.5.Had s equaled 15,the interval estimate would be 37 5.0.

After calculating the sample size needed to estimate a population proportion to within 0.05,you have been told that the maximum allowable error (B)must be reduced to just 0.025.If the original calculation led to a sample size of 1000,the sample size will now have to be:

Two independent samples of sizes 50 and 50 are randomly selected from two populations to test the difference between the population means, .The sampling distribution of the sample mean difference is:

The t-distribution for developing a confidence interval for a mean has _____ degrees of freedom.

If the standard error of the sampling distribution of the sample proportion is 0.0324 for samples of size 200,then the population proportion must be 0.30.

As the sample size increases,the t-distribution becomes more similar to the ________ distribution.

Introduction to Data Analysis and Decision Making

Describing the Distribution of a Single Variable

Finding Relationships Among Variables

Probability and Probability Distributions

Normal, binomial, poisson, and Exponential Distributions

Decision Making Under Uncertainty

Sampling and Sampling Distributions

Hypothesis Testing

Regression Analysis: Estimating Relationships

Regression Analysis: Statistical Inference

Time Series Analysis and Forecasting

Introduction to Optimization Modeling

Optimization Modeling: Applications

Introduction to Simulation Modeling

Simulation Models

Filters

Exam 8: Confidence Interval Estimation

What is the probability of a t-value smaller than 1.00?

If the odds of a horse winning a race are 2 to 1,then the probability of this horse winning the race is_____.

In general,increasing the confidence level will narrow the confidence interval,and decreasing the confidence level widens the interval.

(A)Construct a 95% confidence interval for . (B)Based on your answer to (A),are you convinced that the gaskets from shift 2 are,on average,wider than those from shift 1? Why or why not?

The standard error of the sampling distribution of the sample proportion ,when the sample size n = 50 and the population proportion p = 0.25,is 0.00375.

The chi-square distribution for developing a confidence interval for a standard deviation has_____ degrees of freedom.

A 90% confidence interval estimate for a population mean is determined to be 72.8 to 79.6.If the confidence level is reduced to 80%,the confidence interval for becomes narrower.

When the samples we want to compare are paired in some natural way,such as pretest/posttest for each person or husband/wife pairs,a more appropriate form of analysis is to not compare two separate variables,but their _____.

From a sample of 500 items,30 were found to be defective.The point estimate of the population proportion defective will be:

The interval estimate 18.5 2.5 was developed for a population mean when the sample standard deviation s was 7.5.Had s equaled 15,the interval estimate would be 37 5.0.

After calculating the sample size needed to estimate a population proportion to within 0.05,you have been told that the maximum allowable error (B)must be reduced to just 0.025.If the original calculation led to a sample size of 1000,the sample size will now have to be:

Two independent samples of sizes 50 and 50 are randomly selected from two populations to test the difference between the population means, .The sampling distribution of the sample mean difference is:

The t-distribution for developing a confidence interval for a mean has _____ degrees of freedom.

If the standard error of the sampling distribution of the sample proportion is 0.0324 for samples of size 200,then the population proportion must be 0.30.

As the sample size increases,the t-distribution becomes more similar to the ________ distribution.

Introduction to Data Analysis and Decision Making

Describing the Distribution of a Single Variable

Finding Relationships Among Variables

Probability and Probability Distributions

Normal, binomial, poisson, and Exponential Distributions

Decision Making Under Uncertainty

Sampling and Sampling Distributions

Hypothesis Testing

Regression Analysis: Estimating Relationships

Regression Analysis: Statistical Inference

Time Series Analysis and Forecasting

Introduction to Optimization Modeling

Optimization Modeling: Applications

Introduction to Simulation Modeling

Simulation Models

Filters