Suppose population 1 consists of all students who picked up all the tests they completed prior to taking the final exam. Suppose population 2 consists of all students who had one or more tests that they completed that were not picked up prior to taking the final exam. Based on years of grading final exams and observing grades, STAT 210 instructors conjecture that the mean final exam grade for all students who picked up all their tests is higher than the mean final exam grade for all students who had one or more tests that were not picked up. A simple random sample of 56 students who picked up all tests they completed was selected, and the mean score on the final exam for this sample of students was 83 with a standard deviation of 10.4. An independent simple random sample of 51 students who had one or more tests that were not picked up was selected, and the mean score on the final exam for this sample of students was 67 with a standard deviation of 24.2. Both distributions are skewed heavily to the left. If appropriate, use this information to test the hypotheses at the \alphaα = .01 level of significance. Are the assumptions met? No, because the distributions are heavily skewed to the left. Yes, because any sample size will work and there are 2 simple random samples. Yes, because both samples are larger than 40 and there are 2 simple random samples. Yes, because only sample sizes of 15 are needed and there are 2 simple random samples.
Suppose population 1 consists of all students who picked up all the tests they completed prior to taking the final exam. Suppose population 2 consists of all students who had one or more tests that they completed that were not picked up prior to taking the final exam.
Based on years of grading final exams and observing grades, STAT 210 instructors conjecture that the mean final exam grade for all students who picked up all their tests is higher than the mean final exam grade for all students who had one or more tests that were not picked up.
A simple random sample of 56 students who picked up all tests they completed was selected, and the mean score on the final exam for this sample of students was 83 with a standard deviation of 10.4. An independent simple random sample of 51 students who had one or more tests that were not picked up was selected, and the mean score on the final exam for this sample of students was 67 with a standard deviation of 24.2. Both distributions are skewed heavily to the left. If appropriate, use this information to test the hypotheses at the \alphaα = .01 level of significance.
Are the assumptions met?
No, because the distributions are heavily skewed to the left.
Yes, because any
Yes, because both samples are larger than 40 and there are 2 simple random samples.
Yes, because only sample sizes of 15 are needed and there are 2 simple random samples.
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