Multiple Choices (4 Points Each)

Chapter 8

1.If the sampled population has a mean 48 and standard deviation 18, then the mean and the standard deviation for the sampling distribution of(X-bar) for n = 9 are:

A.48 and 18

B.48 and 9

C.16 and 6

D.48 and 6

E.48 and 2

2.A manufacturing company measures the weight of boxes before shipping them to the customers. If the box weights have a population mean and standard deviation of 90 lbs. and 24 lbs. respectively, then based on a sample size of 36 boxes, the probability that the average weight of the boxes will be more than 94 lbs. is:

A.34.13%

B.84.13%

C.15.87%

D.56.36%

E.16.87%

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

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 the above

E.None of the above

4.In a manufacturing process a machine produces bolts that have an average length of 3 inches with a variance of .03. If we randomly select three bolts from this process: What is the probability the mean length of the bolt is more than 3.16 inches?

A.5.48%

B.97.72%

C.94.52%

D.44.52%

E.2.28%

5.Whenever the population has a normal distribution, the sampling distribution ofis normal or near normal distribution:

A.For only large sample sizes

B.For only small sample sizes

C.For any sample size

D.For only samples of size 30 or more

Chapter 9

7.The width of a confidence interval will be:

A.Narrower for 99% confidence than 95% confidence

B.Narrower for a sample size of 100 than for a sample size of 200

C.Wider for 95% confidence than 90% confidence

D.Wider when the sample standard deviation (s) is small than when s is large

7.As standard deviation increases, samples size _____________ to achieve a specified level of confidence.

A.Increases

B.Decreases

C.Remains the same

8. When the level of confidence and sample standard deviation remain the same, a confidence interval for a population mean based on a sample of n = 100 will be ______________ a confidence interval for a population mean based on a sample of n = 150.

A.Wider than

B.Narrower than

C.Equal to

9.When a confidence interval for a population proportion is constructed for a sample size n =30 and the value of p=.4, the interval is based on:

A.The Z distribution without continuity correction

B.The Z distribution with continuity correction

C.Skewed distribution

D.None of the above

10..In a manufacturing process a random sample of 9 bolts manufactured has a mean length of 3 inches with a variance of .09. What is the 90% confidence interval for the true mean length of the bolt?

A.2.8355 to 3.1645

B.2.5065 to 3.4935

C.2.8140 to 3.1860

D.2.4420 to 3.5580

E.2.9442 to 3.0558

11.The internal auditing staff of a local manufacturing company performs a sample audit each quarter to estimate the proportion of accounts that are delinquent (more than 90 days overdue). For this quarter, the auditing staff randomly selected 400 customer accounts and found that 80 of these accounts were delinquent. What is the 99% confidence interval for the proportion of all delinquent customer accounts at this manufacturing company?

A..1608 to .2392

B..1992 to .2008

C..1671 to .2329

D..1485 to .2515

E..1714 to .2286

12.The internal auditing staff of a local manufacturing company performs a sample audit each quarter to estimate the proportion of accounts that are current (between 0 and 60 days after billing). The historical records show that over the past 8 years 70 percent of the accounts have been current. Determine the sample size needed in order to be 95% confident that the sample proportion of the current customer accounts is within .03 of the true proportion of all current accounts for this company.

A.1842

B.1548

C.897

D.632

E.1267

Chapter 10

13.When testing a null hypothesis about a single population mean and the population standard deviation is unknown, if the sample size is less than 30, one compares the computed test statistic for significance with a value from the ___________ distribution.

A.t

B.Z

C.Binomial

D.Skewed distribution

14.For a given hypothesis test, if we do not reject H₀and H₀is true.

A.No error has been committed

B.Type I error has been committed

C.Type II error has been committed

D.Type III error has been committed

15.If a null hypothesis is not rejected at a significance level of .05, it will ______ be rejected at a significance level of .01

A.Always

B.Sometimes

C.Never

16.If a two-sided null hypothesis is not rejected for a single mean at a given significance level, the corresponding one-sided null hypothesis (i.e., the same sample size, the same standard deviation and the same mean) will _________ be rejected at the same significance level.

A.Always

B.Sometimes

C.Never

17.A professional basketball player is averaging 21 points per game. He will be retiring at the end of this season. The team has multiple options to replace him. However, the owner feels that signing a replacement is only justified, if he can average more than 22 points per game. Which of the following are the appropriate hypotheses for this problem?

A.H₀:m21 vs.H_a:m> 21

B.H₀:m22 vs.H_a:m> 22

C.H₀:m21 vs.H_a:m< 21

D.H₀:m22 vs.H_a:m< 22

18. When carrying out a large sample test of H0:m= 10 vs. Ha:m> 10 by using a critical value, we reject H0 at level of significanceawhen the calculated test statistic is:

A.Less than z_a

B.Less than- z_a

C.Greater than z_a/2

D.Greater than z_a

E.Less than the p value

Chapter 13

19. In a simple linear regression analysis, the correlation coefficient (a) and the slope (b) _____ have the same sign.

A.Always

B.Sometimes

C.Never

20. The least squares regression line minimizes the sum of the

A.Differences between actual and predicted Y values

B.Absolute deviations between actual and predicted Y values

C.Absolute deviations between actual and predicted X values

D.Squared differences between actual and predicted Y values

E.Squared differences between actual and predicted X values

21. The ___________ theR²and the __________ the s (standard error), the stronger the relationship between the dependent variable and the independent variable.

A.Higher, lower

B.Lower, higher

C.Lower, lower

D.Higher, higher

22.In simple regression analysis, the quantity that gives the amount by which Y (dependent variable) changes for a unit change in X (independent variable) is called the

A.Coefficient of determination

B.Slope of the regression line

C.Y intercept of the regression line

D.Correlation coefficient

E.Standard error

23.A simple bivariate regression analysis with 21 observations would yield ________ degrees of freedom error and _________ degrees of freedom total.

A.1, 20

B.18, 19

C.19, 20

D.1, 19

E.18, 20

24.The correlation coefficient may assume any value between

A.0 and 1

B.-and

C.0 and 8

D.-1 and 1

E.-1 and 0

25. In simple regression analysis, if the correlation coefficient is a positive value, then

A.The Y intercept must also be a positive value

B.The coefficient of determination can be either positive or negative, depending on the value of the slope

C.The least squares regression equation could either have a positive or a negative slope

D.The slope of the regression line must also be positive

E.The standard error of estimate can either have a positive or a negative value