Question 1 of 20 1.0 Points 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 40 country CD recordings of Willie Nelson has been examined. The average playing time of these recordings is 51.3 minutes, and the standard deviation is s = 5.8 minutes. Using an appropriate t-multiplier, construct a 95% confidence interval for the mean playing time of all Willie Nelson recordings. Place your LOWER limit, in minutes, rounded to 2 decimal places, in the first blank. For example, 56.78 would be a legitimate entry. [removed] . Place your UPPER limit, in minutes, rounded to 2 decimal places, in the second blank. For example, 67.89 would be a legitimate entry. [removed]  Question 2 of 20 1.0 Points 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 lawyer researched the average number of years served by 45 different justices on the Supreme Court. The average number of years served was 13.8 years with a standard deviation of 7.3 years. What is the 95% confidence interval estimate for the average number of years served by all Supreme Court justices? Place your limits,  rounded to 1 decimal place , in the blanks. Place you lower limit in the first blank. [removed]  Place your upper limit in the second blank.  [removed] When entering your answer do not use any labels or symbols. Simply provide the numerical value. For example, 12.3 would be a legitimate entry.  Question 3 of 20 1.0 Points 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, .

1. Question 1 of 20
1.0 Points
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 40 country CD recordings of Willie Nelson has
been examined. The average playing time of these recordings is
51.3 minutes, and the standard deviation is s = 5.8 minutes.
Using an appropriate t-multiplier, construct a 95% confidence
interval for the mean playing time of all Willie Nelson
recordings.
Place your LOWER limit, in minutes, rounded to 2 decimal
places, in the first blank. For example, 56.78 would be a
legitimate entry. [removed] .
Place your UPPER limit, in minutes, rounded to 2 decimal
places, in the second blank. For example, 67.89 would be a
legitimate entry. [removed]
Question 2 of 20

2. 1.0 Points
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 lawyer researched the average number of years served by 45
different justices on the Supreme Court. The average number of
years served was 13.8 years with a standard deviation of 7.3
years. What is the 95% confidence interval estimate for the
average number of years served by all Supreme Court
justices? Place your limits,
rounded to 1 decimal place
, in the blanks. Place you lower limit in the first
blank. [removed] Place your upper limit in the second
blank. [removed] When entering your answer do not use any
labels or symbols. Simply provide the numerical value. For
example, 12.3 would be a legitimate entry.
Question 3 of 20
1.0 Points
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:

3. 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 90% 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. [removed]
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. [removed]
Question 4 of 20
1.0 Points
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:

4. 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. [removed]
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. [removed]
Question 5 of 20
1.0 Points
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:

5. 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. [removed]
Place your UPPER limit, in hours, rounded to 1 decimal place,
in the second blank. For example, 12.3 would be a legitimate
entry. [removed]
Question 6 of 20
1.0 Points
Accepted characters
: numbers, decimal point markers (period or comma), sign

6. 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 percent defective for parts produced by a manufacturing
process is targeted at 4%. The process is monitored daily by
taking samples of sizes n = 160 units. Suppose that today’s
sample contains 14 defectives.
How many units would have to be sampled to be 95% confident
that you can estimate the fraction of defective parts within 2%
(using the information from today’s sample--that is using the
result that
^
p = 0.0875
)?
Place your answer, as a whole number, in the blank. For
example 567 would be a legitimate entry. [removed]
Question 7 of 20
1.0 Points
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

7. "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: [removed] Round your answer to 4 decimal places as
necessary. For example, 0.1357 would be a legitimate entry.
Part 2 of 3 -
Question 8 of 20
1.0 Points
A food snack manufacturer samples 15 bags of pretzels off the
assembly line and weighed their contents. If the sample mean is
10.0 and the sample standard deviation is 0.15, find the 95%
confidence interval estimate for the true mean.
[removed] A.(9.96, 10.04)
[removed] B.(9.68, 10.32)
[removed] C.(9.97, 10.80)
[removed] D.(9.92, 10.08)
Question 9 of 20
1.0 Points
The t- distribution for developing a confidence interval for a
mean has _____ degrees of freedom.

8. [removed] A.n - 1
[removed] B.n - 2
[removed] C.n
[removed] D.n + 1
Question 10 of 20
1.0 Points
Which of the following will make a confidence interval
narrower and more precise?
[removed] A.Smaller sample size and lower confidence level
[removed] B.Larger sample size and higher confidence level
[removed] C.Smaller sample size and higher confidence level
[removed] D.Larger sample size and lower confidence level
Question 11 of 20
1.0 Points
A researcher wishes to know, with 98% confidence, the
percentage of women who wear shoes that are too small for
their feet. A previous study conducted by the Academy of
Orthopedic Surgeons found that 80% of women wear shoes that
are too small for their feet. If the researcher wants her estimate
to be within 3% of the true proportion, how large a sample is
necessary?
[removed] A.966
[removed] B.683

9. [removed] C.183
[removed] D.484
Question 12 of 20
1.0 Points
A recent study of 750 Internet users in Europe found that 35%
of Internet users were women. What is the 95% confidence
interval estimate for the true proportion of women in Europe
who use the Internet?
[removed] A.0.321 < p < 0.379
[removed] B.0.316 < p < 0.384
[removed] C.0.309 < p < 0.391
[removed] D.0.305 < p < 0.395
Question 13 of 20
1.0 Points
At a large department store, the average number of years of
employment for a cashier is 5.7 with a standard deviation of 1.8
years. If the number of years of employment at this department
store is normally distributed, what is the probability that a
cashier selected at random has worked at the store for over 10
years?
[removed] A.0.4916
[removed] B.0.9916
[removed] C.0.0084

10. [removed] D.0.0054
Question 14 of 20
1.0 Points
A previous study of nickels showed that the standard deviation
of the weight of nickels is 150 milligrams. How many nickels
does a coin counter manufacturer need to weigh so that she can
be 98% confident that her sample mean is within 25 milligrams
of the true average weight of a nickel?
[removed] A.36
[removed] B.196
[removed] C.239
[removed] D.139
Question 15 of 20
1.0 Points
If you increase the confidence level, the confidence interval
____________.
[removed] A.decreases
[removed] B.may increase or decrease, depending on the sample
data
[removed] C.increases
[removed] D.stays the same
Question 16 of 20

11. 1.0 Points
Compute
P(
t
20
_< - 0.95)
where t
20
has a t-distribution with 20 degrees of freedom.
[removed] A.0.5334
[removed] B.0.1767
[removed] C.0.8233
[removed] D.0.6466
Question 17 of 20
1.0 Points
In a study of elephants a researcher wishes to determine the
average weight of a certain subspecies of elephants. From
previous studies, the standard deviation of the weights of
elephants in this subspecies is known to be 1500 pounds. How
many elephants does the researcher need to weigh so that he can
be 80% confident that the average weight of elephants in his
sample is within 350 pounds of the true average weight for this
subspecies?
[removed] A.166

12. [removed] B.31
[removed] C.50
[removed] D.39
Question 18 of 20
1.0 Points
In order to be accepted into a top university, applicants
must score within the top 5% on the SAT exam. Given that SAT
test scores are normally distributed with a mean of 1000 and a
standard deviation of 200, what is the lowest possible score a
student needs to qualify for acceptance into the university?
[removed] A.1330
[removed] B.1400
[removed] C.1250
[removed] D.1100
Part 3 of 3 -
Question 19 of 20
1.0 Points
A 90% confidence interval estimate for a population mean is
determined to be 72.8 to 79.6. If the confidence level is reduced
to 80%, the confidence interval becomes narrower.
[removed] True
[removed] False
Question 20 of 20
1.0 Points

13. In general, increasing the confidence level will narrow the
confidence interval, and decreasing the confidence level widens
the interval.
[removed] True
[removed] False
Number 6 and 16 I could not properly inset the symbol. Contact
me if a confusion occur.