Standard Deviation — Test Answers

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A utility company hires pollsters to knock on random doors in different parts of town to survey residents about the cost of their electric bill. Would this study be biased? Why or why not?

A
No, it is not biased. All residents of the town will have the opportunity to respond.
B
Yes, it is biased. Some of the residents who are surveyed may not want to respond to someone who knocks at their door.
C
No, it is not biased. All residents who are surveyed will want to respond.
D
Yes, it is biased. Only certain parts of the town were surveyed.
3

A supervisor finds the mean number of miles that the employees in a department live from work. He finds and . Which statement must be true?

Question illustration
A
z37 is within 1 standard deviation of the mean.
B
z37 is between 1 and 2 standard deviations of the mean.
C
z37 is between 2 and 3 standard deviations of the mean.
D
z37 is more than 3 standard deviations of the mean.
4

A simple random sample of size n is drawn from a normally distributed population, and the mean of the sample is , while the standard deviation is s. What is the 90% confidence interval for the population mean? Use the table below to help you answer the question.Confidence Level90%95%99%z*-score1.6451.962.58

Question illustration
A
x Overbar plus-or-minus StartFraction 0.90 times s Over StartRoot n EndRoot EndFraction
Option A
B
x Overbar plus-or-minus StartFraction 1.645 times s Over StartRoot n EndRoot EndFraction
Option B
C
x Overbar plus-or-minus StartFraction 1.96 times s Over StartRoot n EndRoot EndFraction
Option C
D
x Overbar plus-or-minus StartFraction 2.58 times s Over StartRoot n EndRoot EndFraction
Option D
5

Opal is collecting data on water levels in different parts of town. She notices that her sample data has a low-value outlier. Which statement must be true?

A
Removing the outlier will not change the spread of the graph of the data set.
B
Removing the outlier will not change the variance of the data set.
C
Removing the outlier will increase the variance of the data set.
D
Removing the outlier will decrease the spread of the graph of the data set.
6

The distribution of the values of a population is shown below, and a simple random sample is drawn from the population. Based on this information alone, can the sample be used to make inferences about the population?

Question illustration
A
No, because the population values appear to be normally distributed.
B
No, because the population values do not appear to be normally distributed.
C
Yes, because the population values appear to be normally distributed.
D
Yes, because the population values do not appear to be normally distributed.
10

Voluntary sampling is one type of sampling method that is not probability based. This means that

A
each member of a population is equally likely to be chosen for the survey.
B
the results of the survey cannot reliably be extended and generalized.
C
the likelihood of a member of the population volunteering to be surveyed is not probable.
D
the results of the survey are not mathematically probable.
12

The histogram below shows the estimated monthly salaries of company employees with different years of experience. How might the graph be misleading?

Question illustration
T
The scale on the y-axis overemphasizes the difference in salaries between different experience levels.
T
The scale on the y-axis underemphasizes the difference in salaries between different experience levels.
T
The scale on the x-axis overemphasizes the difference in salaries between different experience levels.
T
The scale on the x-axis underemphasizes the difference in salaries between different experience levels.

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Standard Deviation — Test Answers — Fall 24 GMS…