**Part 1 of 3 **

4.0/ 7.0 Points

**Question 1 of 20**

1.0/ 1.0 Points

**Accepted characters**: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), E or e (used in scientific notation). **NOTE:** For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where a and b need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The percent defective for parts produced by a manufacturing process is targeted at 4%. The process is monitored daily by taking samples of sizes n = 160 units. Suppose that todays sample contains 14 defectives.

How many units would have to be sampled to be 95% confident that you can estimate the fraction of defective parts within 2% (using the information from todays samplethat is using the result that )?

**Question 2 of 20**

0.0/ 1.0 Points

**Accepted characters**: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), E or e (used in scientific notation). **NOTE:** For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where a and b need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A sample of 9 production managers with over 15 years of experience has an average salary of $71,000 and a sample standard deviation of $18,000.

**Question 3 of 20**

0.0/ 1.0 Points

**Accepted characters**: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), E or e (used in scientific notation). **NOTE:** For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where a and b need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The personnel department of a large corporation wants to estimate the family dental expenses of its employees to determine the feasibility of providing a dental insurance plan. A random sample of 12 employees reveals the following family dental expenses (in dollars): 115, 370, 250, 593, 540, 225, 177, 425, 318, 182, 275, and 228.

Construct a 99% confidence interval estimate for the standard deviation of family dental expenses for all employees of this corporation.

Place your LOWER limit, in dollars rounded to 1 decimal place, in the first blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 98.4 would be a legitimate entry. __175.5__

**Question 4 of 20**

1.0/ 1.0 Points

**Accepted characters**: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), E or e (used in scientific notation). **NOTE:** For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where a and b need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

**Question 5 of 20**

1.0/ 1.0 Points

**Accepted characters**: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), E or e (used in scientific notation). **NOTE:** For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where a and b need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

**Question 6 of 20**

0.0/ 1.0 Points

**Accepted characters**: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), E or e (used in scientific notation). **NOTE:** For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where a and b need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

**Question 7 of 20**

1.0/ 1.0 Points

**Accepted characters**: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), E or e (used in scientific notation). **NOTE:** For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where a and b need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

**Part 2 of 3 **

11.0/ 11.0 Points

**Question 8 of 20**

1.0/ 1.0 Points

A sample of 23 European countries found that the variance of life expectancy was 7.3 years. What is the 95% confidence interval estimate for the variance of life expectancy in Europe?

A.27.2 < < 118.3

B.5.6 < < 10.3

C.4.4 < < 14.6

D.28.9 < < 115.0

Answer Key:

**Question 9 of 20**

1.0/ 1.0 Points

If you increase the confidence level, the confidence interval ____________.

A.stays the same

B.increases

C.decreases

D.may increase or decrease, depending on the sample data

Answer Key:

**Question 10 of 20**

1.0/ 1.0 Points

The average gas mileage of a certain model car is 26 miles per gallon. If the gas mileages are normally distributed with a standard deviation of 1.3, find the probability that a randomly selected car of this model has a gas mileage between 25.8 and 26.3 miles per gallon.

A.0.15

B.0.85

C.0.70

D.0.30

Answer Key:

**Question 11 of 20**

1.0/ 1.0 Points

A researcher wishes to know, with 98% confidence, the percentage of women who wear shoes that are too small for their feet. A previous study conducted by the Academy of Orthopedic Surgeons found that 80% of women wear shoes that are too small for their feet. If the researcher wants her estimate to be within 3% of the true proportion, how large a sample is necessary?

A.966

B.683

C.183

D.484

Answer Key:

**Question 12 of 20**

1.0/ 1.0 Points

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

A..06

B.16.667

C.30

D.0.60

Answer Key:

**Question 13 of 20**

1.0/ 1.0 Points

The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and = 0.20 is

A.0.7342

B.0.5316

C.0.2658

D.0.4684

Answer Key:

**Question 14 of 20**

1.0/ 1.0 Points

A food snack manufacturer samples 15 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 10.0 and the sample standard deviation is 0.15, find the 95% confidence interval estimate for the true mean.

A.(9.96, 10.04)

B.(9.68, 10.32)

C.(9.97, 10.80)

D.(9.92, 10.08)

Answer Key:

**Question 15 of 20**

1.0/ 1.0 Points

Compute where t20 has a t-distribution with 20 degrees of freedom.

A.0.1767

B.0.8233

C.0.6466

D.0.5334

Answer Key:

**Question 16 of 20**

1.0/ 1.0 Points

At a large department store, the average number of years of employment for a cashier is 5.7 with a standard deviation of 1.8 years. If the number of years of employment at this department store is normally distributed, what is the probability that a cashier selected at random has worked at the store for over 10 years?

A.0.4916

B.0.9916

C.0.0084

D.0.0054

Answer Key:

**Question 17 of 20**

1.0/ 1.0 Points

Which of the following will make a confidence interval narrower and more precise?

A.Smaller sample size and higher confidence level

B.Larger sample size and lower confidence level

C.Smaller sample size and lower confidence level

D.Larger sample size and higher confidence level

Answer Key:

**Question 18 of 20**

1.0/ 1.0 Points

A recent study of 750 Internet users in Europe found that 35% of Internet users were women. What is the 95% confidence interval estimate for the true proportion of women in Europe who use the Internet?

A.0.321 < p < 0.379

B.0.316 < p < 0.384

C.0.309 < p < 0.391

D.0.305 < p < 0.395

Answer Key:

**Part 3 of 3 **

2.0/ 2.0 Points

**Question 19 of 20**

1.0/ 1.0 Points

As a general rule, the normal distribution is used to approximate the sampling distribution of the sample proportion, , only if the sample size n is greater than 30.

True

False

Answer Key:

**Question 20 of 20**

1.0/ 1.0 Points

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 becomes narrower.

True

False

Answer Key:

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