Question 1168909: On average, offenders released from state prisons in California tend to commit their first parole violation 4.1 months after release from prison, and the standard deviation for this population of offenders is 2.3. A researcher interested in the effects of a post-release vocational training course for offenders believes that providing job skills and job placement services to ex-offenders will affect their chances of success while on parole. The researcher took a random sample of offenders released from prisons in California (n=81) and had them participate in the vocational training course. The researcher found that the average amount of time before offenders committed their first parole violation was 4.5 months for the sample studied. Use these data to answer the following questions.
15. Assuming a two-tailed (non-directional) test, state the null and alternative hypotheses using the notation discussed in the online lectures.
I GOT H0=4.5 AM I CORRECT?
16. Assuming that α=.05, report the critical z-values for this test.
I GOT +/- 1.96 AM I CORRECT?
17. What is the observed z-score for the sample mean?
I GOT Z=-1.57 AM I CORRECT?
18. From the results of this test, would you choose to reject the null hypothesis or fail to reject the null hypothesis?
I GOT FAIL TO REJECT AM I CORRECT?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! Ho:mean=4.1
Ha::mean not 4.1 units hrs.
alpha=0.05 p{reject Ho|Ho true}
test stat z=(xbar -mean)/sigma/sqrt(n)
15.No, Ho=4.1, what you are testing against.
16. yes
17. z=(4.5-4.1)*sqrt(81)/2.3=1.57
yes
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18. yes
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