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MATH 110 - Introduction to Statistics Module 5
Typology: Exams
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Exam Exam Page 1 Suppose that you take a sample of size 50 from a population that is not normally distributed. Can the sampling distribution of x̄ be approximated by a normal probability distribution? Yes, the sample size can be approximated by a normal probablity ditribution because the sample size is greater than 30.
n ≤ (0.05 x 1200 ) = 60 n ≤ 60 The sample size (n) has to be less than or equal to 60 n ≤ 60 The sample size (n) has to be less than or equal to 60
Exam Page 4 Suppose that in a very large city 9.8 % of the people have more than two jobs. Suppose that you take a random sample of 70 people in that city, what is the probability that 9 % or more of the 70 have more than two jobs? We want P(Z>-0.23). From the standard normal table, we find: P(Z>-.23)=1- P(Z<-.23)=1-.40905=.59095. So there is a .60257 probability that the percentage of the sample that have more than two jobs is more than 9 %. -1.0 points Instructor Comments The value stated in the conclusion is not correct. Answer Key Suppose that in a very large city 9.8 % of the people have more than two jobs. Suppose that you take a random sample of 70 people in that city, what is the probability that 9 % or more of the 70 have more than two jobs? Now we find the z-score: We want P(Z>-0.23). From the standard normal table, we find: P(Z>-.23)=1- P(Z<-.23)=1-.40905=.59095. So there is a .60257 probability that the percentage of the sample that have more than two jobs is more than 9 %.