Question

Really need help ASAP!! please look

Answer 1

A researcher wishes to determine if aerobic exercise improves mental performance immediately following the exercise. He plans to have high school students participate in 30 minutes of aerobic exercise and then take a standard test of their reasoning skills. Suppose the scores of high school students on this test of reasoning skills immediately after 30 minutes of aerobic exercise follow a Normal distribution with mean μ and standard deviation σ = 4. Suppose also that, in the general population of all high school students, scores on the test of reasoning skills follow a Normal distribution with mean 25 and standard deviation σ = 4. The researcher, therefore, decides to test the following hypotheses.
H0 : μ = 25, Ha : μ > 25
To do so, the researcher has 10,000 high school students do 30 minutes of aerobic exercise and then, immediately following the exercise, take the test. The mean score for these students is = 25.2 and the P-value is less than 0.0001.


It is appropriate to conclude which of the following?
A. The researcher has conclusively proved that, for high school students, 30 minutes of aerobic exercise substantially improves mental performance.
B. The researcher has strong evidence that, for high school students, 30 minutes of aerobic exercise substantially improves mental performance.
C. The researcher has moderate evidence that, for high school students, 30 minutes of aerobic exercise substantially improves mental performance.
D. None of the above



In a recent study of the prevalence of sexually transmitted diseases, a simple random sample of 35,000 Americans were selected and it was found that 20.1% reported having at least one STD. A hypothesis test for a difference from the expected 20% was found to be highly significant, though the difference is quite small. The explanation is that
A. it was an aberrant sample.
B. the sample size is very large.
C. the value of 20.1% is large compared to the hypothesized value of 20%.
D. All of the above