Deck 18: Samples and Blocks

Question 1

Ten different families were tested for the average number of gallons of water they used per day before and after viewing a conservation video.A 90% confidence interval for the difference of the means after and before the training, $\mu _ { A } - \mu _ { B }$ was determined to be (-10.8, -4.2).

A)We know that 90% of families will use between 4.2 and 10.8 fewer gallons of water each day after viewing the conservation video.
B)Based on this sample, we are 90% confident that the average decrease in daily water consumption after viewing the conservation video is between 4.2 and 10.8 gallons.
C)We are 90% confident that a randomly selected family who has viewed the video will use between 4.2 and 10.8 more gallons of water per day compared to a randomly selected
Family who has not viewed the video.
D)Based on this sample, we are 90% confident that the average increase in daily water consumption after viewing the conservation video is between 4.2 and 10.8 gallons.
E)We are 90% confident that a randomly selected family who has viewed the video will use between 4.2 and 10.8 fewer gallons of water per day compared to a randomly selected
Family who has not viewed the video.

Answer 1

Based on this sample, we are 90% confident that the average decrease in daily water consumption after viewing the conservation video is between 4.2 and 10.8 gallons.

Question 2

A high school coach uses a new technique in training middle distance runners.He records the times for 4 different athletes to run 800 meters before and after this training.A 95% confidence interval for the difference of the means before and after the training, $\mu _ { B } - \mu _ { A }$ was determined to be (2.6, 4.3).

A)We are 95% confident that a randomly selected middle distance runner at this high school will have a time for the 800-meter run that is between 2.6 and 4.3 seconds shorter after
The training than before the training.
B)We know that 95% of the middle distance runners shortened their times between 2.6 and 4.3 seconds after the training.
C)Based on this sample, with 95% confidence, the average time for the 800-meter run for middle distance runners at this high school is between 2.6 and 4.3 seconds longer after
The new training.
D)Based on this sample, with 95% confidence, the average time for the 800-meter run for middle distance runners at this high school is between 2.6 and 4.3 seconds shorter after
The new training.
E)We know that 95% of all random samples done on runners at this high school will show that the mean time difference before and after the training is between 2.6 and 4.3 seconds.

Answer 2

Based on this sample, with 95% confidence, the average time for the 800-meter run for middle distance runners at this high school is between 2.6 and 4.3 seconds shorter after
The new training.

Question 3

Previous surveys reported that more men than women trade stocks onlinE.A local brokerage firm randomly selected a sample of investors.They found that 45 out of 234 men traded online and 42 out of 251 women traded onlinE.The 95% confidence interval for the difference in proportions is

A)4% to 9%
B)-4% to 9%
C)2% to 12%
D)-2% to 12%
E)-2% to -4%

Answer 3

-4% to 9%

Question 4

A mid-sized company has decided to implement an enterprise resource planning (ERP) system, and management suspects that many of its employees are concerned about the planned implementation.Managers are considering holding informational workshops to help decrease anxiety levels among employees.To determine whether such an approach would be effective, they randomly select 16 employees to participate in a pilot workshop.These employees were given a questionnaire to measure anxiety levels about ERP before and after participating in the workshop.To determine if anxiety levels about ERP decreases as a result of the workshop, they should use a

A)one-tailed test of two proportions.
B)two-tailed test of two independent means.
C)one-tailed test of two independent means.
D)two-tailed paired t-test.
E)one-tailed paired t-test.

Question 5

A mid-sized company has decided to implement an enterprise resource planning (ERP) system, and management suspects that many of its employees are concerned about the planned implementation.Managers are considering holding informational workshops to help decrease anxiety levels among employees.They randomly select 16 employees to participate in a pilot workshop.These employees were given a questionnaire to measure anxiety levels about ERP before and after participating in the workshop.
If we let d = post-workshop anxiety level - pre-workshop anxiety level, the correct alternative hypothesis to determine if this approach was successful is

A) $\mu _ { d } = 0$
B) $\mu _ { d } < 0$
C) $\mu _ { d } > 0$
D) $\mu _ { d } \neq 0$
E) $\mu _ { d } \leq 0$

Question 6

An army depot that overhauls ground mobile radar systems is interested in improving its processes.One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system.The shop floor supervisor believes that having standard work procedures in place will reduce the time required for troubleshooting this component.Time (in minutes) required troubleshooting this component without and with the standard work procedure is recorded for a sample of 19 employees. assuming that we define our differences as Time without standard work procedure - Time with standard work procedure, the correct alternative hypothesis is

A) $\mu _ { d } = 0$ .
B) $\mu _ { d } < 0$ .
C) $\mu _ { d } > 0$ .
D) $\mu _ { d } \neq 0$ .
E) None of the above.

Question 7

Before being released to market, a drug company tests a new allergy medication for potential side effects.A random sample of 160 individuals with allergies was selected for the study.
The new allergy medication was randomly assigned to 80 of them, and another popular allergy medication already on the market (Brand C ) was assigned to the rest.Out of the 80 given the new allergy medication, 14 reported drowsiness; 22 of the 80 taking Brand C reported drowsiness.The 95% confidence interval for the difference in proportions reporting drowsiness is -0.028 to 0.228.Which of the following is correct?

A)We are 95% confident that there is no difference between the proportions of patients reporting drowsiness for the two allergy medications.
B)We are 95% confident that there is a difference between the proportions of patients reporting drowsiness for the two allergy medications.
C)We are 95% confident that the proportion of patients reporting drowsiness is higher for the new allergy medication.
D)We are 95% confident that the proportion of patients reporting drowsiness is lower for the new allergy medication.
E)There will be a significant difference between the proportions 95% of the time.

Question 8

An agricultural company wanted to know if a new insecticide would increase corn yields.
Eight test plots showed an average increase of 3.125 bushels per acrE.The standard deviation of the increases was 2.911 bushels per acre .Determine a 90% confidence interval for the mean increase in yield.

A)(2.435, 3.815)
B)(1.175, 5.075)
C)(2.435, 5.075)
D)(1.175, 3.815)
E)(-5.075, -3.815)

Question 9

An army depot that overhauls ground mobile radar systems is interested in improving its processes.One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system.The shop floor supervisor believes that having standard work procedures in place will reduce the time required fortroubleshooting this component.Time (in minutes) required troubleshooting this component
Without and with the standard work procedure is recorded for a sample of 19 employees.In order to determine if having a standard work procedure in place reduces troubleshooting time, they should use

A)a test of two proportions.
B)a two-tailed test of two independent means.
C)a one-tailed test of two independent means.
D)a two-tailed paired t-test.
E)a one-tailed paired t-test.

Question 10

An army depot that overhauls ground mobile radar systems is interested in improving its processes.One problem involves troubleshooting a particular component that has a high failure rate after it has been repaired and reinstalled in the system.The shop floor supervisor believes that having standard work procedures in place will reduce the time required for troubleshooting this component.Time (in minutes) required troubleshooting this component without and with the standard work procedure is recorded for a sample of 19 employees.Thestandard error of the mean difference is $$\begin{array} { | c | c | c | } \hline \begin{array} { c } \text { Without Standard } \\\text { Work Procedure }\end{array} & \begin{array} { c } \text { With Standard } \\\text { Work Procedure }\end{array} & \begin{array} { c } \text { Difference } \\\text { Without - With }\end{array} \\\hline 142 & 119 & 23 \\\hline 144 & 118 & 26 \\\hline 153 & 126 & 27 \\\hline 148 & 119 & 29 \\\hline 146 & 121 & 25 \\\hline 149 & 125 & 24 \\\hline 138 & 116 & 22 \\\hline 145 & 120 & 25 \\\hline 153 & 124 & 29 \\\hline 160 & 138 & 22 \\\hline 163 & 135 & 28 \\\hline 170 & 144 & 26 \\\hline 169 & 142 & 27 \\\hline 151 & 128 & 23 \\\hline 152 & 131 & 21 \\\hline 167 & 141 & 26 \\\hline 164 & 140 & 24 \\\hline 165 & 140 & 25 \\\hline 163 & 138 & 25 \\\hline\end{array}$$

A)25.105
B)2.307
C)0.529
D)4.3589
E)None of the above.

Question 11

Using the sample paired data below, construct a 90% confidence interval for the population mean of all differences x-y

$\begin{array}{|l|l|l|l|l|l|}\hline x & 5.0 & 4.7 & 4.4 & 5.1 & 6.4 \\\hline y & 4.7 & 3.5 & 4.0 & 5.8 & 4.1 \\\hline\end{array}$

A) $( - 0.69,2.09 )$
B) $( 0.22,7.48 )$
C) $( - 0.37,1.77 )$
D) $( - 0.07,1.47 )$
E) $( - 0.48,1.88 )$

Question 12

A mid-sized company has decided to implement an enterprise resource planning (ERP) system, and management suspects that many of its employees are concerned about the planned implementation.Managers are considering holding informational workshops to help decrease anxiety levels among employees.They randomly select 16 employees to participate in a pilot workshop.These employees were given a questionnaire to measure anxiety levels about ERP before and after participating in the workshop.At the 90% confidence level, what is the margin of error for the mean difference in anxiety levels pre- and post-workshop?

$\begin{array}{|l|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|}\hline \text { Pre-workshop anxiety level } & 7 & 6 & 9 & 5 & 6 & 7 & 5 & 7 & 6 & 4 & 3 & 2 & 1 & 3 & 4 & 2 \\\hline \text { Post-workshop anxiety level } & 4 & 3 & 7 & 3 & 4 & 5 & 4 & 6 & 5 & 3 & 2 & 2 & 1 & 3 & 4 & 3 \\\hline \text { Difference (Post - Pre) } & -3 & -3 & -2 & -2 & -2 & -2 & -1 & -1 & -1 & -1 & -1 & 0 & 0 & 0 & 0 & 1 \\\hline\end{array}$

A) $1.753$
B) $1.147$
C) $0.287$
D) $0.503$
E) $2.010$

Question 13

Ten different families are tested for the number of gallons of water a day they use before and after viewing a conservation video.Construct a 90% confidence interval for the mean of the differences.

$\begin{array}{|l|l|l|l|l|l|l|l|l|l|l|}\hline \text { Before } & 33 & 33 & 38 & 33 & 35 & 35 & 40 & 40 & 40 & 31 \\\hline \text { After } & 34 & 28 & 25 & 28 & 35 & 33 & 31 & 28 & 35 & 33 \\\hline\end{array}$

A) $( 1.8,7.8 )$
B) $( 2.5,7.1 )$
C) $( 3.8,5.8 )$
D) $( 1.5,8.1 )$
E) $( 2.1,7.5 )$

Question 14

Which of the following is not an assumption and/or condition for the paired t-test?

A)Nearly Normal Condition
B)Independent Groups Assumption
C)Paired Data Assumption
D)Randomization Condition
E)All of the above