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 H0: ? = 500 Ha: ? < 500 based on measuring the amount of ginger root in a SRS of 100 capsules. Suppose the results of the test fail to reject H0 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.
c. 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
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