Question 1

Use the following 
According to U.S. Census data, 71.6% of Americans are age 21 and over. The provided figure shows possible sampling distributions for the proportion of a sample age 21 and over, for samples of size n = 50, n = 125, and n = 250.
  Match the sample sizes (n = 50, n = 125, and n = 250) to their sampling distribution.
-Sample C: n = _____________

Accepted Answer

The answer of Use the following 
According to U.S. Census...

Question 2

Use the following 
According to ESPN.com, the average number of yards per game for all NFL running backs with at least 50 attempts in the 2011 season was 49 yards/game. A sample of 20 running backs from the 2011 season averaged 46.54 yards/game.
-Is 49 yards/game a parameter or statistic?
A) Parameter
B) Statistic

Accepted Answer

A parameter is a numerical value that describes a characteristic of a population. Since 49 yards/game is the average for all NFL running backs with at least 50 attempts in the 2011 season, it is a parameter.

Question 3

Use the following 
According to ESPN.com, the average number of yards per game for all NFL running backs with at least 50 attempts in the 2011 season was 49 yards/game. A sample of 20 running backs from the 2011 season averaged 46.54 yards/game.
-Is 46.54 yards/game a parameter or statistic?
A) Parameter
B) Statistic

Accepted Answer

A statistic is a measure that describes a sample, while a parameter describes an entire population. Since 46.54 yards/game is the average for a sample of 20 running backs, it is a statistic.

Question 4

Use the following 
According to ESPN.com, the average number of yards per game for all NFL running backs with at least 50 attempts in the 2011 season was 49 yards/game. A sample of 20 running backs from the 2011 season averaged 46.54 yards/game.
-Two boxplots are shown. One boxplot corresponds to the yards/game for a random sample of n = 20 running backs. The other boxplot represents the values in a sampling distribution of 1,000 means of yards/game for samples of size n = 20.
   Which boxplot represents the sample? Which boxplot represents the sampling distribution? Briefly explain how you know.

Accepted Answer

The answer of Use the following 
According to ESPN.com, the...

Question 5

Use the following 
Identify if each of the following statements is a proper interpretation of a 95% confidence interval.
-I am 95% sure that this interval will contain the population parameter.
A) Correct
B) Incorrect

Accepted Answer

A 95% confidence interval means that if we were to take many samples and build a confidence interval from each sample, we would expect about 95% of those intervals to contain the true population parameter.

Question 6

Use the following 
Identify if each of the following statements is a proper interpretation of a 95% confidence interval.
-I am 95% sure that this interval will contain the sample statistic.
A) Correct
B) Incorrect

Accepted Answer

A 95% confidence interval is about the population parameter, not the sample statistic. It means we are 95% confident that the interval contains the true population parameter, not the sample statistic.

Question 7

Use the following 
Identify if each of the following statements is a proper interpretation of a 95% confidence interval.
-95% of the population values will fall within this interval.
A) Correct
B) Incorrect

Accepted Answer

A 95% confidence interval means that if we were to take many samples and build a confidence interval from each sample, we would expect 95% of those intervals to contain the true population parameter, not that 95% of the population values fall within the interval.

Question 8

Use the following 
Identify if each of the following statements is a proper interpretation of a 95% confidence interval.
-The probability that the population parameter is in this interval is 0.95.
A) Correct
B) Incorrect

Accepted Answer

A 95% confidence interval means that if we were to take many samples and build a confidence interval from each sample, we would expect 95% of those intervals to contain the population parameter. It does not mean there is a 95% probability that the specific interval calculated from a single sample contains the population parameter.

Question 9

Use the following 
Identify if each of the following statements is a proper interpretation of a 95% confidence interval.
-95% of the possible samples from this population will have sample statistics in this particular interval.
A) Correct
B) Incorrect

Accepted Answer

A 95% confidence interval means that if we were to take many samples and build a confidence interval from each, about 95% of those intervals would contain the true population parameter, not that 95% of samples will have statistics within this interval.

Question 10

In 2010, the Centers for Disease Control and Prevention estimated 9.4% of children under the age of 18 had asthma. They reported the standard error to be 0.35%. Assuming that the sampling distribution is symmetric and bell-shaped, find a 95% confidence interval.

Accepted Answer

The answer of In 2010, the Centers for Disease Control...

Question 11

Use the following 
A sample of 148 college students reports sleeping an average of 6.85 hours on weeknights, with a margin of error of 0.35 hours. Based on this information, identify each of the following as plausible or not for the average amount of sleep college students get on weeknights.
-6.6 hours
A) Plausible
B) Not plausible

Accepted Answer

The plausible range for the average amount of sleep is 6.85 ± 0.35 hours, which is 6.5 to 7.2 hours. Since 6.6 hours falls within this range, it is plausible.

Question 12

Use the following 
A sample of 148 college students reports sleeping an average of 6.85 hours on weeknights, with a margin of error of 0.35 hours. Based on this information, identify each of the following as plausible or not for the average amount of sleep college students get on weeknights.
-7.5 hours
A) Plausible
B) Not plausible

Accepted Answer

The plausible range for the average amount of sleep is 6.85 ± 0.35 hours, which is 6.5 to 7.2 hours. Since 7.5 hours is outside this range, it is not plausible.

Question 13

Use the following 
A sample of 148 college students reports sleeping an average of 6.85 hours on weeknights, with a margin of error of 0.35 hours. Based on this information, identify each of the following as plausible or not for the average amount of sleep college students get on weeknights.
-8 hours
A) Plausible
B) Not plausible

Accepted Answer

The plausible range for the average amount of sleep is 6.85 ± 0.35 hours, which is from 6.5 to 7.2 hours. Since 8 hours is outside this range, it is not plausible.

Question 14

Decreasing the confidence level (say, from 95% to 85%) will cause the width of a typical confidence interval to
A) increase.
B) decrease.
C) remain the same.

Accepted Answer

Decreasing the confidence level reduces the margin of error, leading to a narrower confidence interval.

Question 15

Use the following
An Internet provider contacts a random sample of 300 customers and asks how many hours per week the customers use the Internet. It found the average amount of time spent on the Internet per week to be about 7.2 hours.
-Define the parameter of interest, using the proper notation.

Accepted Answer