Question 1

$$\text { Identify the confidence interval used in the figure below. }$$

Accepted Answer

A)  90% 
B)  95% 
C)  98% 
D)  99%

Question 2

A study of 100 apple trees showed that the average number of apples per tree was 2000. The standard deviation of the population is 150. Which of the following is the 95% confidence interval for the mean
Number of apples for all trees?

Accepted Answer

A)  (1975.3, 2024.7) 
B)  (1970.6, 2029.4) 
C)  (1967.7, 2032.3) 
D)  (1965.1, 2034.9)

Question 3

A recent poll of 700 people who work indoors found that 278 of them smoke. If the researchers want to be 98% confident of their results to within 3.5%, how large a sample is necessary?

Accepted Answer

A)  751 
B)  1062 
C)  1301 
D)  532

Question 4

A report states that 46% of home owners had a vegetable garden. How large a sample is needed to estimate the

Accepted Answer

A)  96 
B)  191 
C)  382 
D)  764

Question 5

The confidence level of an interval estimate of a parameter is the probability that the interval estimator
will contain the parameter.

Accepted Answer

A) True 
 B)False

Question 6

A study of 90 bolts of carpet showed that their average length was 180 yards. The standard deviation of the population is 10 yards. Which of the following is the 99% confidence interval for the mean length per
Bolt of carpet?

Accepted Answer

A)  (177.55, 182.45) 
B)  (173.49, 186.51) 
C)  (176.74, 183.26) 
D)  (177.28, 182.72)

Question 7

In a study of 100 new cars, 29 of them were white. Find $\hat { \mathrm { p } }$ and $\hat { \mathrm { q } }$ where $\hat { \mathrm { p } }$ is the proportion of new cars that is white.

Accepted Answer

A)  $\hat { p } = 0.29 , \hat { q } = 0.29$ 
B)  $\hat { \mathrm { p } } = 0.29 , \hat { \mathrm { q } } = 0.71$ 
C)  $\hat { \mathrm { p } } = 0.71 , \hat { \mathrm { q } } = 0.29$ 
D)  $\hat { \mathrm { p } } = 0.71 , \hat { \mathrm { q } } = 0.71$

Question 8

A study of 60 professors showed that the time they spent on the average in creating test questions was 17.0 minutes per question. The standard deviation of the population is 2. Which of the following is the 98% confidence interval for the average number of minutes it takes to create a test question?

Accepted Answer

A)  (15.99, 18.01) 
B)  (16.58, 17.42) 
C)  (16.40, 17.60) 
D)  (12.35, 21.65)

Question 9

The (estimated) standard error of the mean is larger than the standard deviation of the sample from which
it was derived.

Accepted Answer

A) True 
 B)False

Question 10

$$\text { If } \hat { \mathrm { p } } \text { is equal to } 0.76 \text {, then } \hat { \mathrm { q } } \text { is equal to }$$

Accepted Answer

A)  0.76 
B)  0.50 
C)  0.42 
D)  0.24

Question 11

Noting that the critical z-value for a 95% confidence interval for a proportion is almost equal to 2, it
can be seen that the required sample size is approximately equal to the reciprocal of the squared desired
margin of error.

Accepted Answer

A) True 
 B)False

Question 12

A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year. Assume a population standard deviation of 23.8 days. What is the 90% confidence interval for the
Average days worked, $\mu$ of all payroll departments?

Accepted Answer

A)  $301.0 < \mu < 319.6$ 
B)  $298.0 < \mu < 322.6$ 
C)  $302.4 < \mu < 318.2$ 
D)  $314.1 < \mu < 316.8$

Question 13

A random sample of 80 voters found that 46% were going to vote for a certain candidate. Find the 95% limit for the population proportion of voters who will vote for that candidate.

Accepted Answer

A)  35.1% < p < 56.9% 
B)  36.0% < p < 56.0% 
C)  36.8% < p < 55.2% 
D)  40.5% < p < 51.5%

Question 14

In a sample of 855 bartenders, 48% heard complaints from patrons about work. If the margin of error was 4.4%, what was the confidence level that was used?

Accepted Answer

A)  90% 
B)  95% 
C)  98% 
D)  99%

Question 15

A food snack manufacturer samples 9 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 9.6 and the sample standard deviation is 0.20, find the 95% confidence interval of the

Accepted Answer

A)  (9.53, 9.67) 
B)  (9.14, 10.06) 
C)  (9.47, 9.73) 
D)  (9.45, 9.75)

Question 16

It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the

Accepted Answer

A)  0.620 < p < 0.780 
B)  0.591 < p < 0.812 
C)  0.584 < p < 0.830 
D)  0.615 < p < 0.805

Question 17

The value for for a 99% confidence interval when is 9.262.

Accepted Answer

A) True 
 B)False

Question 18

A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval
of the

Accepted Answer

The answer of A sample of 400 racing cars showed...

Question 19

A researcher conducted a study of the access speed of 30 hard drives and concluded that his maximum error of estimate was 20. If he were to conduct a second study to reduce the maximum error of estimate to
4, about how many hard drives should he include in his new sample?

Accepted Answer

A)  30 
B)  60 
C)  150 
D)  750

Question 20

A previous study of nickels showed that the the standard deviation of the weight of nickels is 150 milligrams. A coin counter manufacturer wishes to find the 99% confidence interval for the average
Weight of a nickel. How many nickels does he need to weigh to be accurate within 15 milligrams?

Accepted Answer

A)  100 
B)  666 
C)  955 
D)  542

Exam 6: Confidence Intervals and Sample Size

$\text { Identify the confidence interval used in the figure below. }$ $\text { Identify the confidence interval used in the figure below. } A) 90% B) 95% C) 98% D) 99%$

A study of 100 apple trees showed that the average number of apples per tree was 2000. The standard deviation of the population is 150. Which of the following is the 95% confidence interval for the mean Number of apples for all trees?

A recent poll of 700 people who work indoors found that 278 of them smoke. If the researchers want to be 98% confident of their results to within 3.5%, how large a sample is necessary?

A report states that 46% of home owners had a vegetable garden. How large a sample is needed to estimate the

The confidence level of an interval estimate of a parameter is the probability that the interval estimator will contain the parameter.

A study of 90 bolts of carpet showed that their average length was 180 yards. The standard deviation of the population is 10 yards. Which of the following is the 99% confidence interval for the mean length per Bolt of carpet?

In a study of 100 new cars, 29 of them were white. Find $\hat { \mathrm { p } }$ and $\hat { \mathrm { q } }$ where $\hat { \mathrm { p } }$ is the proportion of new cars that is white.

A study of 60 professors showed that the time they spent on the average in creating test questions was 17.0 minutes per question. The standard deviation of the population is 2. Which of the following is the 98% confidence interval for the average number of minutes it takes to create a test question?

The (estimated) standard error of the mean is larger than the standard deviation of the sample from which it was derived.

$\text { If } \hat { \mathrm { p } } \text { is equal to } 0.76 \text {, then } \hat { \mathrm { q } } \text { is equal to }$

Noting that the critical z-value for a 95% confidence interval for a proportion is almost equal to 2, it can be seen that the required sample size is approximately equal to the reciprocal of the squared desired margin of error.

A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year. Assume a population standard deviation of 23.8 days. What is the 90% confidence interval for the Average days worked, $\mu$ of all payroll departments?

A random sample of 80 voters found that 46% were going to vote for a certain candidate. Find the 95% limit for the population proportion of voters who will vote for that candidate.

In a sample of 855 bartenders, 48% heard complaints from patrons about work. If the margin of error was 4.4%, what was the confidence level that was used?

A food snack manufacturer samples 9 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 9.6 and the sample standard deviation is 0.20, find the 95% confidence interval of the

It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the

The value for for a 99% confidence interval when is 9.262.

A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the

A researcher conducted a study of the access speed of 30 hard drives and concluded that his maximum error of estimate was 20. If he were to conduct a second study to reduce the maximum error of estimate to 4, about how many hard drives should he include in his new sample?

A previous study of nickels showed that the the standard deviation of the weight of nickels is 150 milligrams. A coin counter manufacturer wishes to find the 99% confidence interval for the average Weight of a nickel. How many nickels does he need to weigh to be accurate within 15 milligrams?

Exam 6: Confidence Intervals and Sample Size

Identify the confidence interval used in the figure below. \text { Identify the confidence interval used in the figure below. } Identify the confidence interval used in the figure below.

A study of 100 apple trees showed that the average number of apples per tree was 2000. The standard deviation of the population is 150. Which of the following is the 95% confidence interval for the mean Number of apples for all trees?

A recent poll of 700 people who work indoors found that 278 of them smoke. If the researchers want to be 98% confident of their results to within 3.5%, how large a sample is necessary?

A report states that 46% of home owners had a vegetable garden. How large a sample is needed to estimate the

The confidence level of an interval estimate of a parameter is the probability that the interval estimator will contain the parameter.

A study of 90 bolts of carpet showed that their average length was 180 yards. The standard deviation of the population is 10 yards. Which of the following is the 99% confidence interval for the mean length per Bolt of carpet?

In a study of 100 new cars, 29 of them were white. Find p^\hat { \mathrm { p } }p^​ and q^\hat { \mathrm { q } }q^​ where p^\hat { \mathrm { p } }p^​ is the proportion of new cars that is white.

The (estimated) standard error of the mean is larger than the standard deviation of the sample from which it was derived.

If p^ is equal to 0.76, then q^ is equal to \text { If } \hat { \mathrm { p } } \text { is equal to } 0.76 \text {, then } \hat { \mathrm { q } } \text { is equal to } If p^​ is equal to 0.76, then q^​ is equal to

Noting that the critical z-value for a 95% confidence interval for a proportion is almost equal to 2, it can be seen that the required sample size is approximately equal to the reciprocal of the squared desired margin of error.

A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year. Assume a population standard deviation of 23.8 days. What is the 90% confidence interval for the Average days worked, μ\muμ of all payroll departments?

A random sample of 80 voters found that 46% were going to vote for a certain candidate. Find the 95% limit for the population proportion of voters who will vote for that candidate.

In a sample of 855 bartenders, 48% heard complaints from patrons about work. If the margin of error was 4.4%, what was the confidence level that was used?

A food snack manufacturer samples 9 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 9.6 and the sample standard deviation is 0.20, find the 95% confidence interval of the

It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the

The value for for a 99% confidence interval when is 9.262.

A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the

A researcher conducted a study of the access speed of 30 hard drives and concluded that his maximum error of estimate was 20. If he were to conduct a second study to reduce the maximum error of estimate to 4, about how many hard drives should he include in his new sample?

A previous study of nickels showed that the the standard deviation of the weight of nickels is 150 milligrams. A coin counter manufacturer wishes to find the 99% confidence interval for the average Weight of a nickel. How many nickels does he need to weigh to be accurate within 15 milligrams?

$\text { Identify the confidence interval used in the figure below. }$ $\text { Identify the confidence interval used in the figure below. } A) 90% B) 95% C) 98% D) 99%$

In a study of 100 new cars, 29 of them were white. Find $\hat { \mathrm { p } }$ and $\hat { \mathrm { q } }$ where $\hat { \mathrm { p } }$ is the proportion of new cars that is white.

$\text { If } \hat { \mathrm { p } } \text { is equal to } 0.76 \text {, then } \hat { \mathrm { q } } \text { is equal to }$

A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year. Assume a population standard deviation of 23.8 days. What is the 90% confidence interval for the Average days worked, $\mu$ of all payroll departments?