Provide an appropriate response. pulation has a normal Construct a 90% confidenc

Question

Provide an appropriate response. pulation has a normal Construct a 90% confidence interval for the population mean, Assume the po distribution. In a recent study of 22 eighth graders, the mean number of hours per week that they played video games was 19.6 with a standard deviation of 5.8 hours. 1) A) (18.63, 20.89) B) (1747, 21.73) Answer: B C) (5.87, 7.98) D) (19.62, 23.12) 2) De termine the point estimate of the population mean for the confidence interval with a lower bound of 19 and an upper bound of 25. B) 25 C) 22 D) 23 A) 19 Answer: C 3) True or False: As the level of confidence increases the margin of error decreases. A) True Answer: B B) False Of all the registered automobiles in California, 8% fail the state emission test. Twelve automobiles are selected at random to undergo an emissions test. What is the probability that more than two of them fail the test? 4) A) 0.1234 Answer: C B) 0.0789 C) 0.0652 D) 0.0281 5) At a cell phone battery plant, 5% of cell phone batteries produced are defective. A quality control engineer randomly collect a sample of 50 batteries from a large shipment from this plant and inspects them for defects. What is the probability at least one of the batteries is defective? A) 0.9231 Answer: A B) 0.8231 C)0.7231 D) 0.6231 The S&P; 500 is a collection of 500 stocks of publicly traded companies. The monthly rates of return of the S&P; 500 since 1950 are normally distributed. The mean rate of return is 0.007233 (0.7233%) and the standard deviation for rate of return is 0.04135 (4.135%). Treating the next 24 months as a simple random sample, what is probability that the mean monthly rate of return will be positive? 6) A) 0.8051 Answer: A B) 0.7051 C) 0.6051 D) 0.5051 According to a CNN report, 7% of the population do not have traditional phones and instead rely on only cell phones. In a random sample of 750 telephones users, what is the probability that more 8% are "cell- phone only"? 7)

Explanation / Answer

Ans:

1)df=22-1=21

critical t value=1.721

90% confidence interval for population mean

=19.6+/-1.721*5.8/sqrt(22)

=19.6+/-2.13

=(17.07,21.33)

2)point estimate=sample mean=(19+25)/2=22

3)False

As,confidence level increases,z or t value increases,so margin of error increases.

4)Binomialdistribution with n=12,p=0.08

P(x>2)=1-P(x<=2)=1-bnomcdf(12,0.08,2)=1-0.9348=0.0652

5)P(x>=1)=1-P(none)=1-(0.95)^50=0.9231

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