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STCC201 Quiz #3 (50 pts)

Name: Solutions / Rec. Section: ______

You must show your work to receive full credit.

Use the information in the following setting to answer questions 1 - 6

With gas prices escalating an environmental group has decided to more rigorously promote the purchase of smaller fuel-efficient cars and trucks. In order to strengthen their case they randomly select 9 vehicles from a certain popular model of SUV. The manufacturer claims that these monstrosities average 22 miles per gallon (MPG). However, the environmental group believes that the actual mileage is less than 22 MPG. The descriptive statistics follow in output 1. Test the appropriate hypothesis at a significance level of 0.01.

1) Ho:  22

Ha:  < 22 (Note that this is a two tailed test)

2) t-crit: df = 8;  = 0.01; t-crit = -2.896

3) t – calc:

4) The decision graphic is:

5) The statistical decision is: Circle only one

A) Reject HoB) Fail to Reject Ho

6) The English interpretation for this hypothesis test is:

At a significance level of 0.01 we can conclude that the average mileage is less than the stated 22 mpg

Use the information in the following setting to answer questions 7 – 11

With the Enron debacle still fresh in everyone’s minds a law student would like to predict what kind of sentence the upper management could receive if convicted of fraud and obstruction of justice. Let’s say that an average sentence for first time offenders is supposed to be 12.5 years. Minitab results for a SRS of 20 persons convicted of fraud and obstruction appear in Output 2. Let  = 0.02.

7)Ho:  = 12.5

Ha:  12.5

8) The statistical decision is: circle only one:

A) Reject HoB) Fail to Reject Ho

9) In one or two sentences, defend the answer you chose in 8 :

Since the P-value is bigger than the stated alpha level we FTR Ho.

10) The English interpretation for this hypothesis test is:

At a significance level of 0.02 there is not enough evidence to conclude that the average sentence for first time offenders is different than 12.5 years.

11) Which of the following is the best interpretation of the P-value [3 pts]

A) Given that the null hypothesis is true, the chance that we get a sample mean 13.81 from a sample of 20 convicted felons is 0.231

B) Regardless of the truth of Ho, the chance that we get a sample mean 13.81 from a sample of 20 convicted felons is 0.231

C) Given that the null hypothesis is true, the chance that we get a sample mean of 13.81 from a sample of any size is 0.231

D) Given that the null hypothesis it true, the chance that we would reject it is 0.231

E) Given that the null hypothesis it not true, the chance that we would reject it is 0.231

Rick GuminaSTCC201quiz3_S02.doc

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