1.
Ginger root is used by many as a dietary supplement. A manufacturer of
supplements produces capsules that are advertised to contain at least 500 mg.
of ground ginger root. A consumer advocacy group doubts this claim and tests
the hypotheses
H
0
:
= 500
H
a
:
< 500
based on measuring the amount of ginger root in a SRS of 100 capsules. Suppose
the results of the test fail to reject
H
0
when, in fact, the alternative hypothesis is true.
In this case the consumer advocacy group will have
a. committed a Type I error.
b. committed a Type II error.
c. no power to detect a mean of 500.
2.
A researcher reports that a test is "significant at 5%." This test will be
a. Significant at 1%.
b. Not significant at 1%.
c. Significant at 10%.
3.
Suppose the average Math SAT score for all students taking the exam this year
is 480 with standard deviation 100. Assume the distribution of scores is normal.
The senator of a particular state notices that the mean score for students in his
state who took the Math SAT is 500. His state recently adopted a new
mathematics curriculum and he wonders if the improved scores are evidence
that the new curriculum has been successful. Since over 10,000 students in his
state took the Math SAT, he can show that the
P
value for testing whether the
mean score in his state is more than the national average of 480 is less than
0.0001. We may correctly conclude that
a. there is strong statistical evidence that the new curriculum has improved
Math SAT scores in his state.
b. although the results are statistically significant, they are not practically
significant, since an increase of 20 points is fairly small.
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View Full Documentc. these results are not good evidence that the new curriculum has improved
Math SAT scores.
4.
I want to construct a 92% confidence interval. The correct
z
* to use is
a. 1.75
b. 1.41
c. 1.645
5.
The teacher of a class of 40 high school seniors is curious whether the mean
Math SAT score μ for the population of all 40 students in his class is greater than
500 or not. To investigate this, he decides to test the hypotheses
H
0
: μ = 500
H
a: μ > 500
at level
= 0.05. To do so, he computes that average Math SAT score of all the
students in his class and constructs a 95% confidence interval for the population
mean. The mean Math SAT score of all the students was 502 and, assuming the
standard deviation of the scores is
= 100, he finds the 95% confidence interval is
502
31. He may conclude
a.
H
0
cannot be rejected at level
= 0.05 because 500 is within confidence
interval.
b.
H
0
cannot be rejected at level
= 0.05, but this must be determined by
carrying out the hypothesis test rather than using the confidence interval.
c. We can be certain that
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 Spring '11
 george
 Normal Distribution, Standard Deviation, Statistical hypothesis testing, researcher

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