The​ quality-control manager at a compact fluorescent light bulb​ (CFL) factory needs to determine whether the mean life of a large shipment of CFLs is equal to 7450 hours. The population standard deviation is 700 hours. A random sample of 49 light bulbs indicates a sample mean life of 7,230 hours. a. At the 0.05 level of​ significance, is there evidence that the mean life is different from 7450 hours? b. Compute the​ p-value and interpret its meaning. c. Construct a 95​% confidence interval estimate of the population mean life of the light bulbs. d. Compare the results of​ (a) and​ (c). What conclusions do you​ reach? e. Compare the results of parts​ (a) through​ (d) to those when the standard deviation is 875 hours.   a. Let μ be the population mean. Determine the null​ hypothesis, H0​, and the alternative​ hypothesis, H1.   H0​: μ ▼   equals= less than or equals≤ greater than or equals≥ not equals≠ enter your response here H1​: μ ▼   not equals≠ equals= greater than> less than< enter your response here Part 2 What is the test​ statistic?   ZSTAT=enter your response here ​(Round to two decimal places as​ needed.) Part 3 What​ is/are the critical​ value(s)?   enter your response here ​(Round to two decimal places as needed. Use a comma to separate answers as​ needed.) Part 4 What is the final​ conclusion?     A. Fail to reject H0. There is not sufficient evidence to indicate that the mean life is different from 7450 hours.   B. Fail to reject H0. There is sufficient evidence to indicate that the mean life is different from 7450 hours.   C. Reject H0. There is not sufficient evidence to indicate that the mean life is different from 7450 hours.   D. Reject H0. There is sufficient evidence to indicate that the mean life is different from 7450 hours. Part 5 b. What is the​ p-value?   enter your response here ​(Round to three decimal places as​ needed.) Part 6 Interpret the meaning of the​ p-value.   The​ p-value is the probability of obtaining a ▼   sample population with a mean ▼   equal to at least as extreme as less extreme than enter your response here ​hours, given that the ▼   alternative null hypothesis is true. Part 7 c. Construct a​ 95% confidence interval estimate of the population mean life of the light bulbs.   enter your response here≤μ≤enter your response here ​(Round to the nearest whole number as​ needed.) Part 8 d. Compare the results of​ (a) and​ (c). What conclusions do you​ reach?     A. The results of​ (a) and​ (c) are the same. There is sufficient evidence to indicate that the mean life is different from 7450 hours.   B. The results of​ (a) and​ (c) are not the same. There is not sufficient evidence to indicate that the mean life is different from 7450 hours.   C. The results of​ (a) and​ (c) are not the same. There is sufficient evidence to indicate that the mean life is different from 7450 hours.   D. The results of​ (a) and​ (c) are the same. There is not sufficient evidence to indicate that the mean life is different from 7450 hours. Part 9 e. Compare the results of parts​ (a) through​ (d) to those when the standard deviation is 875. When the standard deviation is 875​, ZSTAT=−1.76​, the​ p-value is 0.078​, and the​ 95% confidence interval is 6,985≤μ≤7,475. State the conclusion for the new standard deviation using the critical value approach. Compare the results to part​ (a).   Using the critical value​ approach, ▼   reject do not reject H0. This result is ▼   the same as different from the result found in part​ (a) because ZSTAT has ▼   increased not changed decreased in absolute value. Part 10 State the conclusion for the new standard deviation using the​ p-value approach. Compare the results to part​ (b).   Using the​ p-value approach, ▼   do not reject reject H0. This result is ▼   different from the same as the result found in part​ (b) because the​ p-value has ▼   not changed. increased. decreased. Part 11 State the conclusion for the new standard deviation using the confidence interval approach. Compare the results to part​ (c).   Using the confidence interval​ approach, ▼   reject do not reject H0. This result is ▼   different from the same as the result found in part​ (c), because the confidence interval has ▼   not changed. become narrower. become wider.

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The​ quality-control manager at a compact fluorescent light bulb​ (CFL) factory needs to determine whether the mean life of a large shipment of CFLs is equal to
7450
hours. The population standard deviation is
700 hours.
A random sample of
49
light bulbs indicates a sample mean life of
7,230
hours.
a. At the
0.05
level of​ significance, is there evidence that the mean life is different from 7450 hours?
b. Compute the​ p-value and interpret its meaning.
c. Construct a
95​%
confidence interval estimate of the population mean life of the light bulbs.
d. Compare the results of​ (a) and​ (c). What conclusions do you​ reach?
e. Compare the results of parts​ (a) through​ (d) to those when the standard deviation is
875
hours.
 
a. Let
μ
be the population mean. Determine the null​ hypothesis,
H0​,
and the alternative​ hypothesis,
H1.
 
H0​:
μ
 
equals=
less than or equals≤
greater than or equals≥
not equals≠
enter your response here
H1​:
μ
 
not equals≠
equals=
greater than>
less than<
enter your response here
Part 2
What is the test​ statistic?
 
ZSTAT=enter your response here
​(Round to two decimal places as​ needed.)
Part 3
What​ is/are the critical​ value(s)?
 
enter your response here
​(Round to two decimal places as needed. Use a comma to separate answers as​ needed.)
Part 4
What is the final​ conclusion?
 
 
A.
Fail to reject
H0.
There
is not
sufficient evidence to indicate that the mean life is different from
7450
hours.
 
B.
Fail to reject
H0.
There
is
sufficient evidence to indicate that the mean life is different from
7450
hours.
 
C.
Reject
H0.
There
is not
sufficient evidence to indicate that the mean life is different from
7450
hours.
 
D.
Reject
H0.
There
is
sufficient evidence to indicate that the mean life is different from
7450
hours.
Part 5
b. What is the​ p-value?
 
enter your response here
​(Round to three decimal places as​ needed.)
Part 6
Interpret the meaning of the​ p-value.
 
The​ p-value is the probability of obtaining a
 
sample
population
with a mean
 
equal to
at least as extreme as
less extreme than
enter your response here
​hours, given that the
 
alternative
null
hypothesis is true.
Part 7
c. Construct a​ 95% confidence interval estimate of the population mean life of the light bulbs.
 
enter your response here≤μ≤enter your response here
​(Round to the nearest whole number as​ needed.)
Part 8
d. Compare the results of​ (a) and​ (c). What conclusions do you​ reach?
 
 
A.
The results of​ (a) and​ (c) are the same. There
is
sufficient evidence to indicate that the mean life is different from
7450
hours.
 
B.
The results of​ (a) and​ (c) are not the same. There
is not
sufficient evidence to indicate that the mean life is different from
7450
hours.
 
C.
The results of​ (a) and​ (c) are not the same. There
is
sufficient evidence to indicate that the mean life is different from
7450
hours.
 
D.
The results of​ (a) and​ (c) are the same. There
is not
sufficient evidence to indicate that the mean life is different from
7450
hours.
Part 9
e. Compare the results of parts​ (a) through​ (d) to those when the standard deviation is
875.
When the standard deviation is
875​,
ZSTAT=−1.76​,
the​ p-value is
0.078​,
and the​ 95% confidence interval is
6,985≤μ≤7,475.
State the conclusion for the new standard deviation using the critical value approach. Compare the results to part​ (a).
 
Using the critical value​ approach,
 
reject
do not reject
H0.
This result is
 
the same as
different from
the result found in part​ (a) because
ZSTAT
has
 
increased
not changed
decreased
in absolute value.
Part 10
State the conclusion for the new standard deviation using the​ p-value approach. Compare the results to part​ (b).
 
Using the​ p-value approach,
 
do not reject
reject
H0.
This result is
 
different from
the same as
the result found in part​ (b) because the​ p-value has
 
not changed.
increased.
decreased.
Part 11
State the conclusion for the new standard deviation using the confidence interval approach. Compare the results to part​ (c).
 
Using the confidence interval​ approach,
 
reject
do not reject
H0.
This result is
 
different from
the same as
the result found in part​ (c), because the confidence interval has
 
not changed.
become narrower.
become wider.
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