Question 1

A random sample of 35 two-year colleges in 2008-2009 collected data on the in-state tuition costs and enrollment totals. Based on the sample, the researchers estimated the mean in-state tuition for all two-year colleges to be $2,380. Which form of statistical inference does this conclusion represent?

Group of answer choices:

a) Interval estimation

b) Point estimation

c) Hypothesis testing

Question 2

A researcher conducted a survey of graduating college students. 350 college students were randomly selected to answer the survey. One of the survey questions asked, "How much do you owe in student loans?" The average student loan debt reported by respondents was $42,576 with a standard deviation of $2,801.

$42,576 is the point estimate for which of the following?

Group of answer choices

a) The mean loan debt of all college students who graduate college.

b) The proportion of all college students who graduate college in debt.

c) The standard deviation of loan debt of all college students who graduate college.

d) The mean salary of all college students who graduate college.

Question 3

Based on survey results, the mean amount of credit card debt for U.S. adults under 35 is $8,724. This point estimate would be unbiased and most accurate if the survey were based on which of the following?

Group of answer choices

a) A random sample of 1,500 U.S. adults under 35

b) A random sample of 2,800 U.S. adults under 35

c) A random sample of 3,000 U.S. college students

d) A national television news station poll with 3,500 responses

Question 4

A random sample of 160 households is selected to estimate the mean amount spent on electric service. A 95% confidence interval was determined from the sample results to be ($151, $216). Which of the following is the correct interpretation of this interval?

Group of answer choices

a) We are 95% confident that the mean amount spent on electric service among the 160 households is between $151 and $216.

b) There is a 95% chance that the mean amount spent on electric service is between $151 and $216.

c) 95% of the households will have an electric bill between $151 and $216.

d) We are 95% confident that the mean amount spent on electric service among all households is between $151 and $216.

Question 5

A survey of a random sample of 1,500 young Americans found that 87% had earned their high school diploma. Based on these results, the 95% confidence interval for the proportion of young Americans who have earned their high school diploma is (0.853,0.887) What is the margin of error for this confidence interval?

Group of answer choices

a) 0.95

b) 0.87

c) 0.017

d) 0.034

Question 6

In which of the following scenarios can we calculate a confidence interval for the population mean? Check all that apply.

Group of answer choices

a) A random sample of 60 cell phone calls is selected and the mean length of calls is determined to be 3.25 minutes with a standard deviation of 4.2 minutes.

b) A random sample of 15 women athletes is selected and their mean weight is determined to be 136 pounds. Female athlete weights are known to be normally distributed with a population standard deviation of 20 pounds.

c) A random sample of 14 cell phone calls is selected and the mean length of calls is determined to be 3.25 minutes with a standard deviation of 4.2 minutes.

d) A random sample of 35 women athletes is selected and their mean weight is determined to be 136 pounds. Female athlete weights are known to be normally distributed with a population standard deviation of 20 pounds.

Question 7

For the following scenario, is the variable is categorical or quantitative?

A poll of students at your college is asked how many hours they work at a job while in school.

Group of answer choices

a) Categorical

b) Quantitative

Question 8

When the sampling distribution of a statistic centers exactly around the parameter it estimates we can say that the statistic is which of the following?

Group of answer choices

a) Normally distributed

b) Equal to the parameter

c) Statistically significant

d) Unbiased

Question 9

A study was conducted to estimate , the mean number of weekly hours that U.S. adults use computers at home. Suppose a random sample of 81 U.S. adults gives a mean weekly computer usage time of 8.5 hours and that from prior studies, the population standard deviation is assumed to be = 3.6 hours.

Based on this information, what would be the point estimate for ?

Group of answer choices

a) 2.36

b) 81

c) 3.6

d) 8.5

Question 10

A study was conducted to estimate , the mean number of weekly hours that U.S. adults use computers at home. Suppose a random sample of 81 U.S. adults gives a mean weekly computer usage time of 8.5 hours and that from prior studies, the population standard deviation is assumed to be = 3.6 hours.

We are 95% confident that the mean number of weekly hours that U.S. adults use computers at home falls between which of the following intervals?

Group of answer choices

a) 8.4 and 8.6

b) 7.3 and 9.7

c) 8.1 and 8.9

d) 7.7 and 9.3

e) 6.5 and 10.5

Question 11

A study was conducted to estimate , the mean number of weekly hours that U.S. adults use computers at home. Suppose a random sample of 81 U.S. adults gives a mean weekly computer usage time of 8.5 hours and that from prior studies, the population standard deviation is assumed to be = 3.6 hours. The 95% confidence interval for the mean, , is (7.7, 9.3).

Which of the following will provide a more informative (i.e., narrower) confidence interval than the 95% confidence interval? Check all that apply.

Group of answer choices

a) Using a sample of size 400 (instead of 81)

b) Using a sample of size 36 (instead of 81)

c) Using a different sample of size 81

d) Using a 90% level of confidence (instead of 95%)

e) Using a 99% level of confidence (instead of 95%)

Question 12

A researcher would like to estimate p, the proportion of U.S. adults who support recognizing civil unions between gay or lesbian couples. Due to a limited budget, the researcher obtained opinions from a random sample of only 2,222 U.S. adults.

With this sample size, the researcher can be 95% confident that the obtained sample proportion will differ from the true proportion (p) by no more than which of the following percentages (answers are rounded)?

Group of answer choices

a) 0.04%

b) 0.75%

c) 2.1%

d) 3%

Question 13

A researcher would like to estimate p, the proportion of U.S. adults who support raising the federal minimum wage.

If the researcher would like to be 95% sure that the obtained sample proportion would be within 2.4% of p (the proportion in the entire population of U.S. adults), what sample size should be used?

Group of answer choices

a) 6,945

b) 1,737

c) 435

d) 42