Quiz_5_Solutions

# Quiz_5_Solutions - 1 Standard error of the mean a is never...

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Unformatted text preview: 1) Standard error of the mean: a) is never larger than the standard deviation of the population. b) decreases as the sample size increases. c) measures the variability of the mean from sample to sample. d) All of the above. 2) The central limit theorem is important in statistics because: a) for a large n, it says the population is approximately normal. b) for any population, it says the sampling distribution of the sample mean is approximately normal, regardless of the sample size. c) for a large n, it says the sampling distribution of the sample mean is approximately normal, regardless of the shape of the population. d) for any sized sample, it says the sampling distribution of the sample mean is approximately normal. 3) If you were constructing a 98% confidence interval of the population mean based on a sample of n=35 where the standard deviation of the sample s = 0.05, the critical value of t will be a) 2.4411 b) 2.4377 c) 2.0322 d) 2.6140 4) A landlord has determined that the number of residents per apartment is normally distributed with a mean of 3.1 and a standard deviation of .4. If 100 apartments were surveyed in the study, what is the standard error of the mean number of residents? a) .310 b) .124 c) .040 d) .004 5) The average score of all bowlers at a particular ally has a mean of 160 and a standard deviation of 60.0. Suppose 64 people bowled today. Find the probability that the average score of the 64 bowlers exceeded 175. a) .4013 b) .0228 c) .0139 d) .9772 Quiz 5 (Chapter 7&8 covered) 6) A wireless company is estimating the average monthly cell phone bill paid by college students. Twenty-five students were randomly sampled and analyzed with the following results: X =\$70 and s^2=225. Construct a 95% confidence interval for the average monthly auto insurance premium, assuming that the amount follows a normal distribution. a) \$70 8.5545 b) \$70 7.7118 c) \$70 6.1917 d) \$70 30.9585 7) Which of the following will increase the size of a confidence interval? a) An increase in n b) A decrease in c) A decrease in d) All of the above 8) The t distribution a) assumes the population is normally distributed. b) approaches the normal distribution as the sample size increases. c) has more area in the tails than does the normal distribution. d) All of the above. 9) True or False? A 90% confidence interval tells us that the true population mean falls inside the interval 90% of the time. 10) True or False? The standardized normal distribution is used to develop a confidence interval estimate of the population proportion when the sample size is sufficiently large. Answers: D C A C B C C D False True ...
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