You want to buy a washing​ machine, and a salesperson tells you that the mean repair costs for Model A and Model B are equal. You research the repair costs. The mean repair cost of 24 Model A washing machines is ​$209. Assume the population standard deviation is ​$20. The mean repair cost of 27 Model B washing machines is ​$215. Assume the population standard deviation is ​$24. At α=0.01, can you reject the​ salesperson's claim? Assume the samples are random and​ independent, and the populations are normally distributed. Complete parts​ (a) through​ (e). ​(a) Identify the claim and state H0 and Ha.   What is the​ claim?     A. The mean repair costs for Model A and Model B are equal.   B. The mean repair cost for Model A is greater than Model B.   C. The mean repair costs for Model A and Model B are different.   D. The mean repair cost for Model A is less than Model B. Let μ1 be the mean repair cost for Model A and let μ2 be the mean repair cost for Model B. What are H0 and Ha​?     A. H0​: μ1≤μ2 Ha​: μ1>μ2   B. H0​: μ1≥μ2 Ha​: μ1<μ2   C. H0​: μ1≠μ2 Ha​: μ1=μ2   D. H0​: μ1<μ2 Ha​: μ1≥μ2   E. H0​: μ1=μ2 Ha​: μ1≠μ2   F. H0​: μ1>μ2 Ha​: μ1≤μ2 ​(b) Find the critical​ value(s) and identify the rejection​ region(s).   The critical​ value(s) is/are negative 2.58 comma 2.58−2.58,2.58. ​(Round to two decimal places as needed. Use a comma to separate answers as​ needed.) What​ is/are the rejection​ region(s)? Select the correct choice below and fill in the answer​ box(es) within your choice. ​(Round to two decimal places as​ needed.)   A. z2.582.58   B. znothing ​(c) Find the standardized test statistic z for μ1−μ2.   z=negative . 15−.15 ​(Round to two decimal places as​ needed.) ​(d) Decide whether to reject or fail to reject the null hypothesis. Choose the correct answer below.     A. Reject H0. The standardized test statistic is not in a rejection region.   B. Fail to reject H0. The standardized test statistic is not in a rejection region.   C. Reject H0. The standardized test statistic is in a rejection region.   D. Fail to reject H0. The standardized test statistic is in a rejection region. ​(e) Interpret the decision in the context of the original claim.   At the 11​% significance​ level, there is insufficient insufficient sufficient evidence to reject support reject the claim that the mean repair costs for Model A are equal to equal to less than greater than different from the mean repair costs for Model B.

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You want to buy a washing​ machine, and a salesperson tells you that the mean repair costs for Model A and Model B are equal. You research the repair costs. The mean repair cost of
24
Model A washing machines is
​$209.
Assume the population standard deviation is
​$20.
The mean repair cost of
27
Model B washing machines is
​$215.
Assume the population standard deviation is
​$24.
At
α=0.01,
can you reject the​ salesperson's claim? Assume the samples are random and​ independent, and the populations are normally distributed. Complete parts​ (a) through​ (e).
​(a) Identify the claim and state
H0
and
Ha.
 
What is the​ claim?
 
 
A.
The mean repair costs for Model A and Model B are equal.
 
B.
The mean repair cost for Model A is greater than Model B.
 
C.
The mean repair costs for Model A and Model B are different.
 
D.
The mean repair cost for Model A is less than Model B.
Let
μ1
be the mean repair cost for Model A and let
μ2
be the mean repair cost for Model B. What are
H0
and
Ha​?
 
 
A.
H0​:
μ1≤μ2
Ha​:
μ1>μ2
 
B.
H0​:
μ1≥μ2
Ha​:
μ1<μ2
 
C.
H0​:
μ1≠μ2
Ha​:
μ1=μ2
 
D.
H0​:
μ1<μ2
Ha​:
μ1≥μ2
 
E.
H0​:
μ1=μ2
Ha​:
μ1≠μ2
 
F.
H0​:
μ1>μ2
Ha​:
μ1≤μ2
​(b) Find the critical​ value(s) and identify the rejection​ region(s).
 
The critical​ value(s) is/are
negative 2.58 comma 2.58−2.58,2.58.
​(Round to two decimal places as needed. Use a comma to separate answers as​ needed.)
What​ is/are the rejection​ region(s)? Select the correct choice below and fill in the answer​ box(es) within your choice.
​(Round to two decimal places as​ needed.)
 
A.
z<negative 2.58−2.58​,
z>2.582.58
 
B.
z<nothing
 
C.
z>nothing
​(c) Find the standardized test statistic z for
μ1−μ2.
 
z=negative . 15−.15
​(Round to two decimal places as​ needed.)
​(d) Decide whether to reject or fail to reject the null hypothesis. Choose the correct answer below.
 
 
A.
Reject
H0.
The standardized test statistic
is not
in a rejection region.
 
B.
Fail to reject
H0.
The standardized test statistic
is not
in a rejection region.
 
C.
Reject
H0.
The standardized test statistic
is
in a rejection region.
 
D.
Fail to reject
H0.
The standardized test statistic
is
in a rejection region.
​(e) Interpret the decision in the context of the original claim.
 
At the
11​%
significance​ level, there is
insufficient
insufficient
sufficient
evidence to
reject
support
reject
the claim that the mean repair costs for Model A are
equal to
equal to
less than
greater than
different from
the mean repair costs for Model B.
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