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 90% 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, 123.4 would be a legitimate entry.

Place your UPPER limit, in dollars rounded to 1 decimal place, in the second blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 567.8 would be a legitimate entry.

Question 6 of 20

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.

After calculating the sample size needed to estimate a population proportion to within 0.05, you have been told that the maximum allowable error (E) 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 . Place your answer, as a whole number in the blank. For example, 2345 would be a legitimate entry.

Question 7 of 20

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.

You are told that a random sample of 150 people from Iowa has been given cholesterol tests, and 60 of these people had levels over the “safe” count of 200. Construct a 95% confidence interval for the population proportion of people in Iowa with cholesterol levels over 200. Place your LOWER limit, rounded to 3 decimal places, in the first blank . For example, .678 would be a legitimate entry. Place your UPPER limit, rounded to 3 decimal places, in the second blank . For example, .789 would be a legitimate entry.

Part 2 of 3 –

Question 8 of 20

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 Reset Selection

Question 9 of 20

1.0 Points

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

A.decreases

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

C.stays the same

D.increases Reset Selection

Question 10 of 20

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 Reset Selection

Question 11 of 20

1.0 Points

When you calculate the sample size for a proportion, you use an estimate for the population proportion; namely f$hat{p}f$ . A conservative value for n can be obtained by using f$hat{p}f$ = ______ .

A.0.01

B.0.10

C.0.50

D.0.05 Reset Selection

Question 12 of 20

1.0 Points

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

A.0.4684

B.0.5316

C.0.2658

D.0.7342 Reset Selection

Question 13 of 20

1.0 Points

In constructing a confidence interval estimate for a population mean, when we replace f$sigma f$ with the sample standard deviation (s), we introduce a new source of variability and the sampling distribution we use is:

A.t -distribution

B.the normal distribution

C.F- distribution

D.chi-square distribution Reset Selection

Question 14 of 20

1.0 Points

Confidence intervals are a function of which of the following three things?

A.The data in the sample, the confidence level, and the sample size

B.The population, the sample, and the standard deviation

C.The sampling distribution, the confidence level, and the degrees of freedom

D.The sample, the variable of interest, and the degrees of freedom Reset Selection

Question 15 of 20

1.0 Points

A previous study of nickels showed that the standard deviation of the weight of nickels is 150 milligrams. How many nickels does a coin counter manufacturer need to weigh so that she can be 98% confident that her sample mean is within 25 milligrams of the true average weight of a nickel?

A.36

B.196

C.239

D.139 Reset Selection

Question 16 of 20

1.0 Points

A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days. What is the 90% confidence interval for the average days worked by employees in all payroll departments?

A.301.0 < f$mu f$ < 319.6

B.298.0 < f$mu f$ < 322.6

C.302.2 < f$mu f$ < 318.4

D.314.1 < f$mu f$ < 316.8 Reset Selection

Question 17 of 20

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 < f$sigma ^{2}f$ < 118.3

B.5.6 < f$sigma ^{2}f$ < 10.3

C.4.4 < f$sigma ^{2}f$ < 14.6

D.28.9 < f$sigma ^{2}f$ < 115.0 Reset Selection

Question 18 of 20

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.0.60

C.30

D.16.667 Reset Selection

Part 3 of 3 –

Question 19 of 20

1.0 Points

The 95% confidence interval for the population mean f$mu f$ , given that the sample size n = 49 and the population standard deviation f$sigma f$ = 7, is f$ar{X}pm 1.96f$ .

True

False

Reset Selection

Question 20 of 20

1.0 Points

The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and f$hat{p}f$ = 0.20 is 0.2341.

True

False

Reset Selection