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Quiz 9.1A . AP Statistics Name: 1. For each of the following settings, deﬁne the parameter of interest and write the appropriate
null and alternative hypotheses for the test that is described.
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(a) Thgean 3333333303 loaves of bread produced at the bakery where you work is supposed
to onapoundi You are the supervisor of quality control at the bakery, and you are
concerned that new personnel are producing loaves that have a mean weight of more than- one ound
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(b) According to the Humane Society®f households in the United States own at least
one cat. You are interested in determining whether the proportion of households of the ’
students at your school that own at least one cat is different from the national proportion. .. .1? P)“- Q ‘ .3..- 1),:
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(:7; .3 .3 3:3“; ' Km 363"“ M33 (33 \312. :3 2.3.9;- . 2. Consider the bakery problem in question 1(a). Suppose you weigh an SRS of bread loaves
and ﬁnd that the mean weight is 1.025 pounds, which yields a P-value of 0.086. M [email protected]‘Pivaluednrthecontext--o£the—problem._ 3:: Q I; II 33 ‘II 3.32 :2. II ‘32:: C:..I3I_ 33.320.3...6‘339113’3.’ 0.3 Q2:353:23 ' We. RM 3 '1‘; t2: I 3333c133 33. t3. (b) What conclusion would you draw at the CL = 0.05 level? At the on = 0.10 level? [Ail 73“ VG" Die “:5? (:5 _ 1;) ﬁgm- a) C} 8 Q!) {135‘ {:5
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i 1.{ Elevenzgcent of the products produced by an industrial process over the past several
3‘ ' ave failed to conform to speciﬁcations. The company modiﬁes the process in an attempt to reduce the rate of nonconformities. In a random sample oi 300 items from a trial
run, the modiﬁed process producess16 nonconforming item. Do these results provide convincing evidence that the modiﬁcation is effective? Support your conclusion with a test :
of signiﬁcance. :
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i 2. The germination rate of seeds is deﬁned as the proportion of seeds that, When properly '“x
planted and watered, sprout and grow. A certain variety of grass seed usually has a
germination rate of 0.80, and a company wants to see if spraying the seeds with a chemical
that is known to change germination rates in other species will change the gemiination rate of
this grass species. They spray 400 seeds with the chemical, and 307 of the seeds germinate.
This produces a 95% conﬁdence interval for the proportion of seeds that germinate of (0.726,
0.809). ' " (a) Suppose the company conducted a test of H 0 : p = 0.8 against the alternative H a : p at 0.8, using 0L 3 0.05. Use the conﬁdence interval to determine whether this test
would reject or fail to reject the null hypothesis. Explain your reasoning. ”(310343; a 2?}; gnlﬂeﬂ Medellin-222%: Arie-wk {Eli‘wgl iimwgﬁ “minimal; iii; , {ENE-‘4? “a ”‘33“ PM“ WMQ’QB
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.9 Quiz 9.3B AP Statistics 7 Name: 1. Sweet corn of a certain variety is known to produce individual ears of corn with a mean
weight of 8 ounces. A farmer is testing a new fertilizer designed to produce iarger ears of -
corn, as measured by their weight. He ﬁnds that 28 randomlyvselected ears of com grown
with this fertilizer have a mean weight of 8.25 ounces and a standard deviation of 0.8 ounces. There are no outliers in the data. (a) Do these samples provide convincing evidence at the on = 0.05 level that the feltilizer had
a positive impact on the weight of the corn ears? Justify your answer. ' cam: Cmﬂ‘gﬂ _ , . (53-99
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t (b) How would your conclusion change if your sample mean had been 8.26 ounces? What
point does this make about statistical signiﬁcance?
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