The Survey of Study Habits and Attitudes (SSHA) is a phychological test that mea

Question

The Survey of Study Habits and Attitudes (SSHA) is a phychological test that measures the motivation, attitude toward school, and study habits of students. Scores range from 0 to 200. The mean score for U.S. college students is abut 115, and the standard deviation is about 30. A teacher who suspects that older students have better attitudes toward school gives that the SSHA to 25 students who are at least 30 years of age. Their mean is x = 127.8.

(a) Assuming that = 30 for the population of older students, carry out a test of

H0 :=115

Ha :>115

Report the P-value of your test, and state your conclusion clearly.

(b) Your test in part (a) required two important assumptions in addition to the assumption that the value of is known. What are they? Which of these assumptions is most important to the validity of your conclusion in part (a)?

Explanation / Answer

answer

Write down the hypotheses (in symbol) to test the teacher's statement.

H0:mu=115

H1 : mu>115

What is the value of the test statistic?

Z = 127.5 115 /30 /s.r(25) = 2.0833

What is the P-value?

P(z>2.0833) approximately 0

conclusion:

There is strong evidence to reject the null hypothesis in favor of the alternative hypothesis, that is, older students seem to have a higher mean score.

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