Exhibit 10.7. A stats professor at a large university hypothesizes that students
ID: 3357479 • Letter: E
Question
Exhibit 10.7.
A stats professor at a large university hypothesizes that students who take statistics in the morning typically do better than those who take it in the afternoon. He takes independently random samples, each of size 36, consisting of students who took a morning and an afternoon class, and compares the scores of each group on a common final test. He finds that the morning group scored an average of 74 with a standard deviation of 8, while the evening group scored an average of 68 with a standard deviation of 10. The population standard deviation of scores is unknown but assumed to be equal for morning and evening classes. Let 1 and 2 represent the population mean final test scores of statistics courses offered in the morning and the afternoon, respectively.
Refer to Exhibit 10.7. At the 1% significance level, does the evidence support the professor's claim?
A) No, since the test statistic is less than the critical value.
B) Yes, since the test statistic is less than the critical value.
C) No, since the test statistic is greater than the critical value.
D) Yes, since the test statistic is greater than the critical value.
Explanation / Answer
The statistical software output for this problem is:
Two sample T summary hypothesis test:
1 : Mean of Population 1
2 : Mean of Population 2
1 - 2 : Difference between two means
H0 : 1 - 2 = 0
HA : 1 - 2 > 0
(with pooled variances)
Hypothesis test results:
Critical value = 2.381
Hence,
We have sufficient evidence to support the professor's claim since the test statistic is greater than the critical value.
Option D is correct.
Difference Sample Diff. Std. Err. DF T-Stat P-value 1 - 2 6 2.1343747 70 2.8111277 0.0032Related Questions
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