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Question 1 of 20
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1.0/
1.0 Points
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Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), "E"
or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST
be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and
"b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas
{9i} is not.
Senior management of a consulting services firm is concerned about a
growing decline in the firm’s weekly number of billable hours. The firm
expects each professional employee to spend at least 40 hours per week on
work. In an effort to understand this problem better, management would like
to estimate the standard deviation of the number of hours their employees
spend on work-related activities in a typical week. Rather than reviewing
the records of all the firm’s full-time employees, the management randomly
selected a sample of size 51 from the available frame. The sample mean and
sample standard deviations were 48.5 and 7.5 hours, respectively.
Construct a 95% confidence interval for the standard deviation of the
number of hours this firm’s employees spend on work-related activities in a
typical week.
Place your LOWER limit, in hours, rounded to 1 decimal place, in the first
blank. For example, 6.7 would be a legitimate entry. 6.2
Place your UPPER limit, in hours, rounded to 1 decimal place, in the second
blank. For example, 12.3 would be a legitimate entry. 9.3
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Question 2 of 20
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1.0/
1.0 Points
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Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), "E"
or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST
be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and
"b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas
{9i} is not.
The personnel department of a large corporation wants to estimate the
family dental expenses of its employees to determine the feasibility of
providing a dental insurance plan. A random sample of 12 employees reveals
the following family dental expenses (in dollars): 115, 370, 250, 593, 540,
225, 177, 425, 318, 182, 275, and 228.
Construct a 99% confidence interval estimate for the standard deviation of
family dental expenses for all employees of this corporation.
Place your LOWER limit, in dollars rounded to 1 decimal place, in the first
blank. Do not use a dollar sign, a comma, or any other stray mark. For
example, 98.4 would be a legitimate entry. 94.7
Place your UPPER limit, in dollars rounded to 1 decimal place, in the
second blank. Do not use a dollar sign, a comma, or any other stray mark.
For example, 567.8 would be a legitimate entry. 304.0
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Question 3 of 20
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1.0/
1.0 Points
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Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), "E"
or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST
be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and
"b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas
{9i} is not.
If a sample has 20 observations and a 95% confidence estimate
for is needed, the appropriate value of the t-multiple required
is 2.093 . Place your answer, rounded to 3 decimal
places, in the blank. For example, 4.567 would be a legitimate entry.
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Question 4 of 20
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1.0/
1.0 Points
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Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), "E"
or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST
be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and
"b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas
{9i} is not.
A sample of 9 production managers with over 15 years of experience has an
average salary of $71,000 and a sample standard deviation of $18,000.
Assuming that s = 18,000 is a reasonable estimate for what
sample size would be needed to ensure that we could estimate the true mean
salary of all production managers with more than 15 years experience within
$4200 if we wish to be 95% confident? Place your answer, as a whole number,
in the blank. Do not use a dollar sign, a comma, or any other stray mark.
For examples, 34 would be a legitimate entry. 71
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Question 5 of 20
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0.0/
1.0 Points
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Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), "E"
or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST
be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and
"b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas
{9i} is not.
The manufacturer of a new compact car claims the miles per gallon (mpg) for
the gasoline consumption is mound-shaped and symmetric with a mean of 24.6
mpg and a standard deviation of 11.2 mpg. If 30 such cars are tested,
what is the probability the average mpg achieved by these 30 cars will be
greater than 27?
Answer: 0.4168 Round
your answer to 4 decimal places as necessary. For example, 0.1357
would be a legitimate entry.
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Feedback: This is a
sampling distribution problem with μ = 24.6. σ = 11.2, and sample size n
= 30.
P(z > 1.173691) = 1 - NORMSDIST(1.173691) = 0.1203
Or you can compute the probability without having to compute z first:
P(x-bar > 27) = 1 - NORMDIST(27, 24.6, 11.2/SQRT(30), TRUE) = 0.1203
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Question 6 of 20
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1.0/
1.0 Points
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Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), "E"
or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST
be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and
"b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas
{9i} is not.
The personnel department of a large corporation wants to estimate the
family dental expenses of its employees to determine the feasibility of
providing a dental insurance plan. A random sample of 12 employees reveals
the following family dental expenses (in dollars): 115, 370, 250, 593, 540,
225, 177, 425, 318, 182, 275, and 228.
Construct a 95% confidence interval estimate for the standard deviation of
family dental expenses for all employees of this corporation.
Place your LOWER limit, in dollars rounded to 1 decimal place, in the first
blank. Do not use a dollar sign, a comma, or any other stray mark. For
example, 123.4 would be a legitimate entry. 104.7
Place your UPPER limit, in dollars rounded to 1 decimal place, in the
second blank. Do not use a dollar sign, a comma, or any other stray mark.
For example, 567.8 would be a legitimate entry. 251.1
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Question 7 of 20
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1.0/
1.0 Points
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Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), "E"
or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST
be used as the decimal point marker.
Complex numbers should be in the form (a + bi) where "a" and
"b" need to have explicitly stated values.
For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas
{9i} is not.
Senior management of a consulting services firm is concerned about a growing
decline in the firm’s weekly number of billable hours. The firm expects
each professional employee to spend at least 40 hours per week on work. In
an effort to understand this problem better, management would like to
estimate the standard deviation of the number of hours their employees
spend on work-related activities in a typical week. Rather than reviewing
the records of all the firm’s full-time employees, the management randomly
selected a sample of size 51 from the available frame. The sample mean and
sample standard deviations were 48.5 and 7.5 hours, respectively.
Construct a 99% confidence interval for the standard deviation of the
number of hours this firm’s employees spend on work-related activities in a
typical week.
Place your LOWER limit, in hours, rounded to 1 decimal place, in the first
blank. For example, 6.7 would be a legitimate entry. 5.9
Place your UPPER limit, in hours, rounded to 1 decimal place, in the second
blank. For example, 12.3 would be a legitimate entry. 10.1
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