ch 9 and 10 Mock Exam

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East Los Angeles College *

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227S

Subject

Chemistry

Date

May 2, 2024

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pdf

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3

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Ch 9 and 10 Mock Exam 1. In a study of police gunfire reports dunng a recent year, 1t was found that among 540 shots fired by New York City police, 182 Iut their targets; and among 283 shots fired by Los Angeles police, 77 hut their targets. a. Usea 0.05 significance level to test the claim that New York City police and Los Angeles police have different proportion of hits. b. Construct a 90 % confidence mterval to estimate the difference between the two proportions of huts.
AVTINIUTIIILE nncaval vi & wicarnio 2. The National Association of Colleges (NAC) reported in 2003 that the mean starting salary for college graduates majoring in management information systems was $40,915 and for psychology major was $27.454. Suppose the NAC data are based on surveys of size 144 for each major, with a standard deviation of $10.000 for the management information systems majors and $7000 for the psychology majors. Construct and interpret a 95% confidence interval for the difference between two means. Wnte a conclusion sentence. 3. Does hypnotism result in a different success rate for men and women who are trying to quut smoking? Researchers at Science magazine analyzed studies mnvolving 5600 male and female smokers. Of the 2800 females, 644 quit smoking; of the 2800 males, 840 quit smoking. Construct a 90% confidence interval for the difference in proportion of males and females, and use the interval to judge whether there is a difference in the proportions. 8. A software manufacturer claims that its spell-checker can reduce spelling errors in text documents. A random sample of nine documents were wrntten and the number of spelling errors counted before and after the spell-checker was used. Assume that the differences are normally distnbuted. Document 1 2 3 4 5 6 7 8 Before 5 3 10 2 0 1 5 0 3 After 2 1 2 0 0 1 0 0 0 Difference 3 2 8 2 0 0 5 0 3 Is there evidence for the manufacturer’s claim? Perform the appropnate hypothesis test, using level of significance a =0.01
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