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Unformatted text preview: Stat 119 Quiz 61) Name:
Red id: Use the following to answer Questions 13:
A 90% conﬁdence interval for the proportion of drivers who change CDs while they are driving is (0.583, 0.657) 3. (2 points) What is the point estimate of the true proportion of drivers who change CD3
while driving? ’ “ _ i“ 2:: beta " Answer (l point) The margin of error for the conﬁdence interval is: iggn iﬁgg a... to Answer a 3. (1 point) What is the best interpretation of the above interval?
A. 90% of the time the true proportion of drivers who change CDs while driving
will be within the interval.
B. 90% of. the time the sample proportion of drivers who change CDs while driving will be within the interval. We are 90% confident that the true proportion of drivers who change CD3 while
driving wiEl be within the interval.
D. We are 90% conﬁdent that the sample proportion of drivers who change CD5 while driving will be within the interval. Use the foliowing information for problems 47 A
A survey conducted at SDSU interviews a random sample of 229 female students and 167 g 2: i :3. admitted to dieting within the past 12 months. gﬁ 4. (3 points) Construct a 95% conﬁdence interval for p, the population proportion of ferna e
SDSU Students whO have bﬁeﬂ 01* . . sees a Mt 5. (1 point) Give a onesentence interpretation of yur conﬁden e interval. h? its ii:
an . sis ﬁeﬁtt shoﬁii him
a t. a a  I 6. (2 points) How many female students would we need to survey in order to reduce the
margin of error to 0.02? a it t i t it 7. (1 point) Suppose the researcher decided that he wanted to obtain a shorter confidence
interval than the one caicuiated above. This could be accompiished by:
A. Using a lower level of conﬁdence. M
13. Using a smaller sample size. K
C. Using a higher love} of confide'aceg
D. Both A) and B) Answer: Use the following information for probiems 89 An article in the Annals of the Association of American Geographers revealed that ooiy 116 of
Bi? randomly seiected residences in Los Angeles County were protected by earthquake
insurance. Do the data provide sufficient evidence to show that less than 40% of the residents of
Los Angeles County are protected by earthquake insurance? Use a 0.05 level of significance. 8. (1 point) Gi __ e two assumptions that must be met in order for a hypothesis test to be valid 52%?g §@ 7 § 3 § 9. Condot a hypothesis test:
1. (2 points) State the nuli and alternative hypotheses. w agQ ﬁg: §§3 gig ll. (2 points) Calculate the test statistic. gag héghe ‘Q_ We... III. (2 points) Calculate the corresponding pwvalue. WQWz: ?{%€ém itgg 1'; ...
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 Spring '07
 Helen
 Statistics, Null hypothesis, Statistical hypothesis testing

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