Question 1

A 99% confidence interval is wider than an 80% confidence interval.

Accepted Answer

A) True 
 B)False

Question 2

It is estimated that 780,000 surgical site infections (SSIs)occur each year.SSIs are the second most common type of healthcare-associated infections in U.S.hospitals and account for an extra $3.5 to $10 billion in healthcare costs per year.The national SSIs rate is 1.9%.A Georgetown medical office was interested in determining if their SSI rate were smaller than the national average.Out of a sample of 277 patients in their study,only one infection occurred.What is the sample size n in this study?

Accepted Answer

A) 780,000 
B) 277 
C) 278 
D) 1 
A) 780,000 
B) 277 
C) 278 
D) 1

Question 3

The level C confidence interval for a proportion p will have a margin of error approximately equal to a specified value m when the sample size satisfies   .What does the p* represent?

Accepted Answer

A) A guessed value of p 
B) A guessed value of   
  
C) The true value of   
  
D) The true value of p 
A) A guessed value of p 
B) A guessed value of   
  
C) The true value of   
  
D) The true value of p

Question 4

It is estimated that 780,000 surgical site infections (SSIs)occur each year.SSIs are the second most common type of healthcare-associated infections in U.S.hospitals and account for an extra $3.5 to $10 billion in healthcare costs per year.The national SSIs rate is 1.9%.A Georgetown medical office was interested in determining if their SSI rate were smaller than the national average.Out of a sample of 277 patients in their study,only one infection occurred.What is the standard error of   
  ?

Accepted Answer

A) 0 
B) Around .004 
C) Greater than .1 
D) None of the above 
A) 0 
B) Around .004 
C) Greater than .1 
D) None of the above

Question 5

The candy company that makes M&M's claims that 10% of the M&M's it produces are green.Suppose that the candies are packaged at random,and the small bags contain 25 M&M's.When we randomly pick a bag of M&M's,we may assume that this represents a simple random sample of size n = 25.Suppose that in a randomly selected small bag of M&M's,there are 5 green M&M's.What is the value of the standard error of   ?

Accepted Answer

A) 0.0063 
B) 0.0794 
C) 0.08 
D) 0.10 
A) 0.0063 
B) 0.0794 
C) 0.08 
D) 0.10

Question 6

It is estimated that 780,000 surgical site infections (SSIs)occur each year.SSIs are the second most common type of healthcare-associated infections in U.S.hospitals and account for an extra $3.5 to $10 billion in healthcare costs per year.The national SSIs rate is 1.9%.A Georgetown medical office was interested in determining if their SSI rate were smaller than the national average.Out of a sample of 277 patients in their study,only one infection occurred.What is an 80% confidence interval for   
  ?

Accepted Answer

A) (.004,.011) 
B) (0,1) 
C) (-.001,.008) 
D) None of the above 
A) (.004,.011) 
B) (0,1) 
C) (-.001,.008) 
D) None of the above

Question 7

Suppose that   =.5,   = .2,n1 = 20,and n2 = 30.What is the test statistic to test the hypothesis H0: p1 = p2?

Accepted Answer

A) 2.228 
B) .026 
C) .3 
D) None of the above 
A) 2.228 
B) .026 
C) .3 
D) None of the above

Question 8

Suppose we have two binomial populations where the true proportion of success is .2 for the first population and .3 for the second population.We take an SRS of size 4 from the first population,and the number of successes is 3.We take an SRS of size 400 from the second population,and the number of successes is 200.What is the mean of   - .1?

Accepted Answer

A) 4 
B) .2 
C) 3.9 
D) None of the above 
A) 4 
B) .2 
C) 3.9 
D) None of the above

Question 9

A simple random sample of 60 households in City 1 is taken.In the sample,there are 45 households that decorate their houses with lights for the holidays.A simple random sample of 50 households is also taken from the neighboring City 2.In the sample,there are 40 households that decorate their houses.We wish to estimate the difference in proportions of households that decorate their houses with lights for the holidays,with a 95% confidence interval.Under the null hypothesis of equality,of the proportions of households that decorate their houses in the two neighboring towns,what is the standard error of the difference in sample proportions?

Accepted Answer

A) 0.040 
B) 0.0795 
C) 0.0802 
D) 0.1125 
A) 0.040 
B) 0.0795 
C) 0.0802 
D) 0.1125

Question 10

Suppose we have two binomial populations where the true proportion of success is .2 for the first population and .3 for the second population.We take an SRS of size 4 from the first population,and the number of successes is 3.We take an SRS of size 400 from the second population,and the number of successes is 200.What is a possible reason that   is not closer to .2?

Accepted Answer

A) Because the sample size is too small 
B) Because of nonresponse bias 
C) Because of sampling variability 
D) All of the above 
A) Because the sample size is too small 
B) Because of nonresponse bias 
C) Because of sampling variability 
D) All of the above

Question 11

A quality manager in a small manufacturing company wants to estimate the proportion of items produced by a very specialized process that fail to meet a customer's specification.Because it is very expensive to determine if an item produced by the process meets the specification,only a very small number of items can be tested.A random sample of 15 items was selected,and in the sample three of them failed.Based on the sample results,the plus four estimate of the true proportion of items that failed to meet the customer's specifications is _______.

Accepted Answer

A)    = 0.200 
B)    = 0.158 
C)    = 0.333 
D)    = 0.263 
E) Not within ± 0.02 of any of the above 
A)    = 0.200 
B)    = 0.158 
C)    = 0.333 
D)    = 0.263 
E) Not within ± 0.02 of any of the above

Question 12

An inspector inspects large truckloads of potatoes to determine the proportion p in the shipment with major defects prior to using the potatoes to make potato chips.If there is clear evidence that this proportion is less than 0.10,she will accept the shipment.To reach a decision,she will test the hypotheses H0: p = 0.10 versus Ha: p < 0.10.To do so,she selects a simple random sample of 150 potatoes from the more than 3000 potatoes on the truck.Only 8 of the potatoes sampled are found to have major defects.What is the value of the large-sample z statistic?

Accepted Answer

A) z = -2.33 
B) z = -1.91 
C) z = 2.33 
D) z = 1.91 
A) z = -2.33 
B) z = -1.91 
C) z = 2.33 
D) z = 1.91

Question 13

An inspector inspects large truckloads of potatoes to determine the proportion p in the shipment with major defects prior to using the potatoes to make potato chips.If there is clear evidence that this proportion is less than 0.10,she will accept the shipment.To reach a decision,she will test the hypotheses H0: p = 0.10 versus Ha: p < 0.10.To do so,she selects a simple random sample of 150 potatoes from the more than 3000 potatoes on the truck.Only 8 of the potatoes sampled are found to have major defects.Compute the value of the large-sample z statistic.What is the P-value for this hypothesis test?

Accepted Answer

A) Less than 0.0002 
B) 0.0098 
C) 0.0284 
D) 0.0568 
A) Less than 0.0002 
B) 0.0098 
C) 0.0284 
D) 0.0568

Question 14

A quality manager in a small manufacturing company wants to estimate the proportion of items produced by a very specialized process that fail to meet a customer's specification.Because it is very expensive to determine if an item produced by the process meets the specification,only a very small number of items can be tested.A random sample of 15 items was selected,and in the sample three of them failed.At the 98% confidence level,what is the margin of error in the plus four estimate of p?

Accepted Answer

A) 0.198 
B) 0.023 
C) 0.235 
D) 0.261 
E) Not within ± 0.01 of any of the above 
A) 0.198 
B) 0.023 
C) 0.235 
D) 0.261 
E) Not within ± 0.01 of any of the above

Question 15

It is estimated that 780,000 surgical site infections (SSIs)occur each year.SSIs are the second most common type of healthcare-associated infections in U.S.hospitals and account for an extra $3.5 to $10 billion in healthcare costs per year.The national SSIs rate is 1.9%.A Georgetown medical office was interested in determining if their SSI rate were smaller than the national average.Out of a sample of 277 patients in their study,only one infection occurred.What is the approximate distribution of   
  ?

Accepted Answer

A) Normal 
B) Uniform 
C) T 
D) F 
A) Normal 
B) Uniform 
C) T 
D) F

Question 16

A simple random sample of 450 residents in the state of New York is taken to estimate the proportion of people who live within 1 mile of a hazardous waste site.If a 95% confidence interval were calculated for a scenario where p = 0.3 and another scenario where p = 0.7,how would the two confidence intervals compare?

Accepted Answer

A) Since the sample proportion in the first scenario is smaller,its confidence interval would be narrower. 
B) Even though the sample proportions are different,the widths of the confidence intervals would be equal. 
C) Since the sample proportion in the second scenario is larger,its confidence interval would be shifted to the right and narrower than the one calculated from the first scenario. 
D) This cannot be determined from the information given. 
A) Since the sample proportion in the first scenario is smaller,its confidence interval would be narrower. 
B) Even though the sample proportions are different,the widths of the confidence intervals would be equal. 
C) Since the sample proportion in the second scenario is larger,its confidence interval would be shifted to the right and narrower than the one calculated from the first scenario. 
D) This cannot be determined from the information given.

Question 17

Suppose that   =.5,   = .2,n1 = 20,and n2 = 30.What is the pooled standard error?

Accepted Answer

A) .12 
B) .01 
C) 0 
D) None of the above 
A) .12 
B) .01 
C) 0 
D) None of the above

Question 18

The large-sample significance test for population proportion is based on a z statistic.

Accepted Answer

A) True 
 B)False

Question 19

The candy company that makes M&M's claims that 10% of the M&M's it produces are green.Suppose that the candies are packaged at random,and the small bags contain 25 M&M's.When we randomly pick a bag of M&M's,we may assume that this represents a simple random sample of size n = 25.Suppose that in a randomly selected small bag of M&M's,there are 5 green M&M's.What is a 99% plus four confidence interval for p,the population proportion of green M&M's?

Accepted Answer

A) (0,0.4061) 
B) (0.0161,0.4283) 
C) (0.0367,0.4461) 
D) (0.0856,0.3971) 
A) (0,0.4061) 
B) (0.0161,0.4283) 
C) (0.0367,0.4461) 
D) (0.0856,0.3971)

Question 20

A simple random sample of 100 athletes is selected from a large high school.In the sample,there are 15 football players.What is the standard error of the sample proportion of football players?

Accepted Answer

A) 0.00128 
B) 0.0357 
C) 0.05 
D) 0.357 
A) 0.00128 
B) 0.0357 
C) 0.05 
D) 0.357

A 99% confidence interval is wider than an 80% confidence interval.

The level C confidence interval for a proportion p will have a margin of error approximately equal to a specified value m when the sample size satisfies .What does the p^* represent?

Suppose that =.5, = .2,n₁ = 20,and n₂ = 30.What is the test statistic to test the hypothesis H₀: p₁= p₂?

Suppose that =.5, = .2,n₁ = 20,and n₂ = 30.What is the pooled standard error?

The large-sample significance test for population proportion is based on a z statistic.

A simple random sample of 100 athletes is selected from a large high school.In the sample,there are 15 football players.What is the standard error of the sample proportion of football players?

Looking at Datadistributions

Looking at Datarelationships

Producing Data

Probability: the Study of Randomness

Sampling Distributions

Introduction to Inference

Inference for Means

Inference for Categorical Data

Inference for Regression

Multiple Regression

One-Way Analysis of Variance

Two-Way Analysis of Variance

Logistic Regression

Nonparametric Tests

Bootstrap Methods and Permutation Tests

Statistics for Quality: Control and Capability

Filters

Exam 8: Inference for Proportions

A 99% confidence interval is wider than an 80% confidence interval.

The level C confidence interval for a proportion p will have a margin of error approximately equal to a specified value m when the sample size satisfies .What does the p* represent?

Suppose that =.5, = .2,n1 = 20,and n2 = 30.What is the test statistic to test the hypothesis H0: p1 = p2?

Suppose that =.5, = .2,n1 = 20,and n2 = 30.What is the pooled standard error?

The large-sample significance test for population proportion is based on a z statistic.

A simple random sample of 100 athletes is selected from a large high school.In the sample,there are 15 football players.What is the standard error of the sample proportion of football players?

Looking at Datadistributions

Looking at Datarelationships

Producing Data

Probability: the Study of Randomness

Sampling Distributions

Introduction to Inference

Inference for Means

Inference for Categorical Data

Inference for Regression

Multiple Regression

One-Way Analysis of Variance

Two-Way Analysis of Variance

Logistic Regression

Nonparametric Tests

Bootstrap Methods and Permutation Tests

Statistics for Quality: Control and Capability

Filters

The level C confidence interval for a proportion p will have a margin of error approximately equal to a specified value m when the sample size satisfies .What does the p^* represent?

Suppose that =.5, = .2,n₁ = 20,and n₂ = 30.What is the test statistic to test the hypothesis H₀: p₁= p₂?

Suppose that =.5, = .2,n₁ = 20,and n₂ = 30.What is the pooled standard error?