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

Question

The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures the motivation, attitude toward school, and study habits of students. Scores range from 0 to 200, with 200 being the highest level of motivation. The mean score for U.S. college students is about 115, and the standard deviation is about 30. A teacher who suspects that older students have better attitudes toward school gives the SSHA to 20 students who are at least 30 years of age.

a) State the null and alternative hypotheses.

b) The mean of her sample is 116.Calculate the z-statistic.

c) Report the P-value of your test, and state your conclusion clearly: was the teacher justified in her suspicion.

Explanation / Answer

a)
Hypothesis:
H0 : mu = 115
Ha : mu > 115

b)
Test statistics:

x = 116 , s = 30 , n = 20

t = ( x - mean) / ( s/sqrt(n))
= ( 116 - 115) / ( 30/sqrt(20))
= 0.1491

c)
P value is calculated using t = 0.1491 with df = 19 at 0.05 significance level
P value = .44152

we fail to reject the null hypothesis.
No, teacher was not justified in her suspicion

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