Question 1

The standard deviation of all possible sample proportions increases as the sample size increases.

Accepted Answer

A) True 
 B)False

Question 2

The chief chemist for a major oil and gasoline production company claims that the regular unleaded gasoline produced by the company contains on average 4 ounces of a certain ingredient.The chemist further states that the distribution of this ingredient per gallon of regular unleaded gasoline is normal and has a standard deviation of 1.2 ounces.What is the probability of finding an average in excess of 4.3 ounces of this ingredient from 100 randomly inspected 1-gallon samples of regular unleaded gasoline?

Accepted Answer

A) .5987 
B) .4013 
C) .9938 
D) .0062 
A) .5987 
B) .4013 
C) .9938 
D) .0062

Question 3

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.Find P(   > 50.5).

Accepted Answer

A) .0002 
B) .7257 
C) .2743 
D) .1389 
A) .0002 
B) .7257 
C) .2743 
D) .1389

Question 4

A common practice in selecting a sample from a large geographic area is multistage cluster sampling.

Accepted Answer

A) True 
 B)False

Question 5

Find P(395.4 x = 20,and n = 100.

Accepted Answer

A) .9786 
B) .9999 
C) .0214 
D) .9893 
A) .9786 
B) .9999 
C) .0214 
D) .9893

Question 6

If a population distribution is known to be normal,then it follows that:

Accepted Answer

A) The sample mean must equal the population mean. 
B) The sample mean must equal the population mean for large samples. 
C) The sample standard deviation must equal the population standard deviation. 
D) All of these. 
E) None of these. 
A) The sample mean must equal the population mean. 
B) The sample mean must equal the population mean for large samples. 
C) The sample standard deviation must equal the population standard deviation. 
D) All of these. 
E) None of these.

Question 7

For nonnormal populations,as the sample size (n)___________________,the distribution of sample means approaches a(n)________________ distribution.

Accepted Answer

A) Decreases;uniform 
B) Increases;normal 
C) Decreases;normal 
D) Increases;uniform 
E) Increases;exponential 
A) Decreases;uniform 
B) Increases;normal 
C) Decreases;normal 
D) Increases;uniform 
E) Increases;exponential

Question 8

As the sample size increases,the standard deviation of the sampling distribution increases.

Accepted Answer

A) True 
 B)False

Question 9

In the upcoming election for governor,the most recent poll,based on 900 respondents,predicts that the incumbent will be reelected with 55 percent of the votes.For the sake of argument,assume that 51 percent of the actual voters in the state support the incumbent governor (p = 0.51).Calculate the probability of observing a sample proportion of voters 0.55 or higher supporting the incumbent governor.

Accepted Answer

A) .0166 
B) .0247 
C) .0082 
D) .9918 
A) .0166 
B) .0247 
C) .0082 
D) .9918

Question 10

If we have a sample size of 100 and the estimate of the population proportion is .10,what is the mean of the sampling distribution of the sample proportion?

Accepted Answer

A) 0.0009 
B) 0.10 
C) 0.03 
D) 0.90 
E) 0.09 
A) 0.0009 
B) 0.10 
C) 0.03 
D) 0.90 
E) 0.09

Question 11

The diameter of small Nerf balls manufactured at a factory in China is expected to be approximately normally distributed with a mean of 5.2 inches and a standard deviation of .08 inches.Suppose a random sample of 20 balls is selected.Find the interval that contains 95.44 percent of the sample means.

Accepted Answer

A) [5.04,5.36] 
B) [5.18,5.22] 
C) [5.16,5.24] 
D) [5.07,5.33] 
A) [5.04,5.36] 
B) [5.18,5.22] 
C) [5.16,5.24] 
D) [5.07,5.33]

Question 12

It has been reported that the average time to download the home page from a government website was 0.9 seconds.Suppose that the download times were normally distributed with a standard deviation of 0.3 seconds.If random samples of 23 download times are selected,describe the shape of the sampling distribution and how it was determined.

Accepted Answer

A) Normal;size of sample meets the Central Limit Theorem requirement. 
B) Normal;the original population is normal. 
C) Skewed;the original population is not a normal distribution. 
D) Cannot be determined with the information that is given. 
A) Normal;size of sample meets the Central Limit Theorem requirement. 
B) Normal;the original population is normal. 
C) Skewed;the original population is not a normal distribution. 
D) Cannot be determined with the information that is given.

Question 13

It has been reported that the average time to download the home page from a government website was 0.9 seconds.Suppose that the download times were normally distributed with a standard deviation of 0.3 seconds.If random samples of 36 download times are selected,80 percent of the sample means will be between what two values symmetrically distributed around the population mean?

Accepted Answer

A) [.648,1.152] 
B) [.836,.964] 
C) [.514,1.280] 
D) [.858,.942] 
A) [.648,1.152] 
B) [.836,.964] 
C) [.514,1.280] 
D) [.858,.942]

Question 14

Sampling error occurs because of incomplete information.

Accepted Answer

A) True 
 B)False

Question 15

For large samples,the sampling distribution of   is approximately normal with a mean of _____.

Accepted Answer

A) μ 
B) μ/√n 
C)    
D) z 
A) μ 
B) μ/√n 
C)    
D) z

Question 16

The number of defectives in 10 different samples of 50 observations each is the following: 5,1,1,2,3,3,1,4,2,3.What is the estimate of the population proportion of defectives?

Accepted Answer

A) .25 
B) .50 
C) .05 
D) .42 
A) .25 
B) .50 
C) .05 
D) .42

Question 17

The population of lengths of aluminum-coated steel sheets is normally distributed with a mean of 30.05 inches and a standard deviation of 0.2 inches.A sample of four metal sheets is randomly selected from a batch.What is the probability that the average length of a sheet is between 30.25 and 30.35 inches long?

Accepted Answer

A) .9773 
B) .0227 
C) .0386 
D) .0215 
A) .9773 
B) .0227 
C) .0386 
D) .0215

Question 18

The chief chemist for a major oil and gasoline production company claims that the regular unleaded gasoline produced by the company contains on average 4 ounces of a certain ingredient.The chemist further states that the distribution of this ingredient per gallon of regular unleaded gasoline is normal and has a standard deviation of 1.2 ounces.What is the probability of finding an average less than 3.85 ounces of this ingredient from 64 randomly inspected 1-gallon samples of regular unleaded gasoline?

Accepted Answer

A) .1587 
B) .8413 
C) .1357 
D) .8643 
A) .1587 
B) .8413 
C) .1357 
D) .8643

Question 19

It has been reported that the average time to download the home page from a government website was 0.9 seconds.Suppose that the download times were normally distributed with a standard deviation of 0.3 seconds.If random samples of 36 download times are selected,what is the probability that the sample mean will be less than 0.84 seconds?

Accepted Answer

A) .1151 
B) .4522 
C) .8849 
D) .5478 
A) .1151 
B) .4522 
C) .8849 
D) .5478

Question 20

The sampling distribution of   must be a normal distribution with mean = 0 and standard deviation = 1.

Accepted Answer

A) True 
 B)False

The standard deviation of all possible sample proportions increases as the sample size increases.

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.Find P( > 50.5).

A common practice in selecting a sample from a large geographic area is multistage cluster sampling.

Find P(395.4 < < 404.6),if the population mean = 400,σ_x = 20,and n = 100.

If a population distribution is known to be normal,then it follows that:

For nonnormal populations,as the sample size (n)___,the distribution of sample means approaches a(n) distribution.

As the sample size increases,the standard deviation of the sampling distribution increases.

If we have a sample size of 100 and the estimate of the population proportion is .10,what is the mean of the sampling distribution of the sample proportion?

The diameter of small Nerf balls manufactured at a factory in China is expected to be approximately normally distributed with a mean of 5.2 inches and a standard deviation of .08 inches.Suppose a random sample of 20 balls is selected.Find the interval that contains 95.44 percent of the sample means.

Sampling error occurs because of incomplete information.

For large samples,the sampling distribution of is approximately normal with a mean of _____.

The number of defectives in 10 different samples of 50 observations each is the following: 5,1,1,2,3,3,1,4,2,3.What is the estimate of the population proportion of defectives?

The sampling distribution of must be a normal distribution with mean = 0 and standard deviation = 1.

An Introduction to Business Statistics

Descriptive Statistics: Tabular and Graphical Methods

Descriptive Statistics: Numerical Methods

Probability

Discrete Random Variables

Continuous Random Variables

Confidence Intervals

Hypothesis Testing

Statistical Inferences Based on Two Samples

Experimental Design and Analysis of Variance

Chi-Square Tests

Simple Linear Regression Analysis

Multiple Regression and Model Building

Process Improvement Using Control Charts

Filters

Exam 7: Sampling and Sampling Distributions

The standard deviation of all possible sample proportions increases as the sample size increases.

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.Find P( > 50.5).

A common practice in selecting a sample from a large geographic area is multistage cluster sampling.

Find P(395.4 < < 404.6),if the population mean = 400,σx = 20,and n = 100.

If a population distribution is known to be normal,then it follows that:

For nonnormal populations,as the sample size (n)___________________,the distribution of sample means approaches a(n)________________ distribution.

As the sample size increases,the standard deviation of the sampling distribution increases.

If we have a sample size of 100 and the estimate of the population proportion is .10,what is the mean of the sampling distribution of the sample proportion?

Sampling error occurs because of incomplete information.

For large samples,the sampling distribution of is approximately normal with a mean of _____.

The number of defectives in 10 different samples of 50 observations each is the following: 5,1,1,2,3,3,1,4,2,3.What is the estimate of the population proportion of defectives?

The sampling distribution of must be a normal distribution with mean = 0 and standard deviation = 1.

An Introduction to Business Statistics

Descriptive Statistics: Tabular and Graphical Methods

Descriptive Statistics: Numerical Methods

Probability

Discrete Random Variables

Continuous Random Variables

Confidence Intervals

Hypothesis Testing

Statistical Inferences Based on Two Samples

Experimental Design and Analysis of Variance

Chi-Square Tests

Simple Linear Regression Analysis

Multiple Regression and Model Building

Process Improvement Using Control Charts

Filters

Find P(395.4 < < 404.6),if the population mean = 400,σ_x = 20,and n = 100.

For nonnormal populations,as the sample size (n)___,the distribution of sample means approaches a(n) distribution.