# QNT 275 Week 5 Quiz

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QNT 275 Week 5 Quiz

Chapter 08, Section 8.2, Problem 011

Correct.

For a data set obtained from a sample, n=80 and x¯=48.80. It is known that σ=4.4.

a. What is the point estimate of μ?

The point estimate is .

b. Make a 97% confidence interval for μ.

Round your answers to two decimal places.

(,)

c. What is the margin of error of estimate for part b?

Round your answer to three decimal places.

E=

Chapter 08, Section 8.2, Problem 015a

Correct.

For a population data set, σ=13.1. How large a sample should be selected so that the margin of error of estimate for a 99% confidence interval for μ is 2.50?

Round your answer up to the nearest whole number.

n=

the tolerance is +/-5%

Chapter 09, Section 9.1, Problem 006

Correct.

Consider H0: μ=55 versus H1: μ≠55.

a. What type of error would you make if the null hypothesis is actually false and you fail to reject it?

What type of error would you make if the null hypothesis is actually true and you reject it?

Chapter 09, Section 9.1, Problem 007

Correct.

Write the null and alternative hypotheses for the following example. Determine if the example is a case of a two-tailed, a left-tailed, or a right-tailed test.

To test if the mean length of experience of airport security guards is different from 3 years.

H0: μ=3

years, H1: μ<3 years, left-tailed test

≤

H0: μ≤3 years, H1: μ3 years, two-tailed test

≠

H0: μ≠3 years, H1: μ=3 years, right-tailed test

H0: μ=3

years, ≠H1: μ≠3 years, two-tailed test

H0: μ=3

years, H1: μ3 years, right-tailed test

Chapter 09, Section 9.2, Problem 022

Consider H0: μ=100 versus H1: μ≠100.

A random sample of 69 observations produced a sample mean of 91. Using α=0.1, would you reject the null hypothesis? The population standard deviation is known to be σ=12.

Chapter 09, Section 9.2, Problem 025b

Correct.

The manufacturer of a certain brand of auto batteries claims that the mean life of these batteries is 45 months. A consumer protection agency that wants to check this claim took a random sample of 24 such batteries and found that the mean life for this sample is 43.05 months. The lives of all such batteries have a normal distribution with the population standard deviation of 4.5 months.

Test the hypothesis H0: μ=45 months versus H1: μ<45 months using the critical-value approach and α=0.02.

H0 is

Chapter 09, Section 9.2, Problem 029a

Lazurus Steel Corporation produces iron rods that are supposed to be 36 inches long. The machine that makes these rods does not produce each rod exactly 36 inches long. The lengths of the rods are normally distributed and vary slightly. It is known that when the machine is working properly, the mean length of the rods is 36 inches. The standard deviation of the lengths of all rods produced on this machine is always equal to 0.035 inch. The quality control department at the company takes a sample of 20 such rods every week, calculates the mean length of these rods, and tests the null hypothesis, μ=36 inches, against the alternative hypothesis, μ≠36 inches. If the null hypothesis is rejected, the machine is stopped and adjusted. A recent sample of 20 rods produced a mean length of 36.015 inches.

Calculate the p-value for this test of hypothesis. Based on this p-value, will the quality control inspector decide to stop the machine and adjust it if he chooses the maximum probability of a Type I error to be 0.05?

Use the normal distribution table. Round your answer to four decimal places.

p-value =

The machine

8th-ed Chapter 09, Section 9.1, Problem 004a

Correct.

Explain if the following is a two-tailed test, a left-tailed test, or a right-tailed test.

H0: μ=45, H1: μ45.

8th-ed Chapter 09, Section 9.1, Problem 004a

Correct.

Explain if the following is a two-tailed test, a left-tailed test, or a right-tailed test.

H0: μ=45, H1: μ45.

Chapter 08, Section 8.1, Intelligent Tutoring Problem 001

Defining estimate, estimator, point estimate, and interval estimation.

Chapter 08, Section 8.1, Intelligent Tutoring Problem 001

The value(s) assigned to a population parameter based on the value of a sample statistic is called an estimate.

You answered correctly! Move on to the next part to add to your understanding of this problem.

A sample statistic used to estimate a population parameter is

You answered correctly! Move on to the next part to add to your understanding of this problem.

.

Attempts: 2 of 3 used

Chapter 08, Section 8.1, Intelligent Tutoring Problem 001

The value of a sample statistic used to estimate a population parameter is called a

Congratulations, you answered correctly!

.

In interval estimation, an interval is constructed around the

Congratulations, you answered correctly!

, and it is stated that this interval is likely to contain the corresponding population parameter.

Chapter 08, Section 8.1, Problem 001

Correct.

Briefly explain the meaning of an estimator and an estimate.

An estimator is the value of a sample statistic used to estimate a population parameter, while an estimate is an interval where one is confident to a certain percent that the value of interest is in the interval.

An estimator is an interval where one is confident to a certain percent that the value of interest is in the interval, while an estimate is the value of a sample statistic used to estimate a population parameter.

An estimator is a prediction of the mean based on the population, while an estimate is a prediction of the mean based on a sample.

An estimator is a sample statistic used to estimate a population parameter, while an estimate is the value(s) assigned to a population parameter based on the value of a sample statistic.

An estimator is the value(s) assigned to a population parameter based on the value of a sample statistic, while an estimate is a sample statistic used to estimate a population parameter.

Chapter 08, Section 8.2, Problem 010

Correct.

Find  z for a  90% confidence level.

Round your answer to two decimal places.

z=

the tolerance is +/-2%

Chapter 08, Section 8.2, Problem 011

For a data set obtained from a sample, n=80 and x¯=46.55. It is known that σ=3.9.

What is the point estimate of μ?

The point estimate is   .

Make a 97% confidence interval for μ.

Round your answers to two decimal places.

(  ,  )

What is the margin of error of estimate for part b?

Round your answer to three decimal places.

E=

Chapter 08, Section 8.2, Problem 017a

Correct.

Determine the sample size for the estimate of μ for the following.

E=2.4, σ=12.35, confidence level=99%.

Round your answer to the nearest integer.

n=

the tolerance is +/-2%

Chapter 08, Section 8.3, Problem 034b

Correct.

For the following, find the area in the appropriate tail of the t distribution.

t=1.711 and n=25.

Round your answer to 3 decimal places.

Area in the

tail is

the tolerance is +/-2%

Chapter 09, Section 9.1, Problem 004a

Correct.

Which of the following is a left-tailed test?

H0: μ=101, H1: μ<101

H0: μ=48, H1: μ≠48

H0: μ=73, H1: μ73

Chapter 09, Section 9.1, Problem 007

Correct.

Write the null and alternative hypotheses for the following example. Determine if the example is a case of a two-tailed, a left-tailed, or a right-tailed test.

To test if the mean length of experience of airport security guards is different from 3 years.

≠H0: μ≠3 years, H1: μ=3 years, right-tailed test

H0: μ=3 years, ≠H1: μ≠3 years, two-tailed test

H0: μ=3 years, H1: μ<3 years, left-tailed test

H0: μ=3 years, H1: μ3 years, right-tailed test

≤H0: μ≤3 years, H1: μ3 years, two-tailed test

Chapter 09, Section 9.2, Problem 014c

Correct.

Consider H0: μ=38 versus H1: μ38. A random sample of 35 observations taken from this population produced a sample mean of 40.26. The population is normally distributed with σ=7.2.

Calculate the p-value. Round your answer to four decimal places.

p=

the tolerance is +/-2%

Chapter 09, Section 9.2, Problem 020a

Correct.

A random sample of 125 observations produced a sample mean of 31. Find the critical and observed values of z for the following test of hypothesis using α=0.01. The population standard deviation is known to be 5 and the population distribution is normal.

H0: μ=28 versus H1: μ≠28.

Round your answers to two decimal places.

zcritical left =

zcritical right =

zobserved =

Chapter 09, Section 9.2, Problem 025b

Correct.

The manufacturer of a certain brand of auto batteries claims that the mean life of these batteries is 45 months. A consumer protection agency that wants to check this claim took a random sample of 24 such batteries and found that the mean life for this sample is 43.05 months. The lives of all such batteries have a normal distribution with the population standard deviation of 4.5 months.

Test the hypothesis H0: μ=45 months versus H1: μ<45 months using the critical-value approach and α=0.1.

H0 is

Chapter 01, Section 1.3, Video Quiz 2

Please view the following video before answering this question. Soda with Callouts

The number of sodas is what type of data?

Discrete.

Continuous.