Quiz 4
Page 1
Name: __________________________
Date: _____________
1. Assume that in a hypothesis test with null hypothesis
μ
0
H :
= 13.0 at
α
=
0.05, that a
value of 11.0 for the sample mean results in the null hypothesis not being rejected. That
corresponds to a confidence interval result of
A)
The 95% confidence interval for the mean does not contain the value 13.0
B)
The 95% confidence interval for the mean contains the value 11.0
C)
There is insufficient information to conclude whether the 95% confidence interval
for the mean contains or does not contain the value 13.0
D)
The 95% confidence interval for the mean contains the value 13.0
2. Nationwide, the average waiting time until electric utility customer service
representative answers a call is 300 seconds per call.
The Gigantic Kilowatt Energy
Company took a sample of 35 calls and found that, on the average, they answered in 240
seconds per call with a standard deviation of 50.
Can the company claim that they are
faster than the average utility?
3. If the observed value is 4, the expected value is 5, and the standard error is 4, then the
test value used for the z test is equal to
4. Using the
z
table in Table E of Appendix C, what are the critical values for a twotailed
test when
α
=
0 03
.
.
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Quiz 4
Page 2
5. The average speed of greyhound dogs is about 18.8 meters per second.
A particular
greyhound breeder claims that her dogs are faster than the average greyhound. In a
sample of 45 of her dogs, they ran, on the average, 19.2 meters per second with a
standard deviation of 1.4.
Is her claim correct if she is willing to accept an error rate of
2.5 out of 100?
A)
Yes, because 1.92 falls in the noncritical region
B)
No, because 0.04 falls in the noncritical region
C)
Yes, because 0.04 falls in the noncritical region
D)
No, because 1.92 falls in the noncritical region
6.
What is the critical
t
value for a righttailed test when
.025
α
=
and d.f. = 12?
7. Are the following statements a valid pair of null and alternative hypothesis?
0
H
:
μ
≥
17
A
H
:
μ
≤
17
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 Spring '10
 dc
 Math, Null hypothesis, Statistical hypothesis testing, test value

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