24. Parameters are a. numerical characteristics of a sample b. numerical charact

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24. Parameters are a. numerical characteristics of a sample b. numerical characteristics of a population c. the averages taken from a sample numerical characteristics ofeither a sample or a population sampl 25. A simple random sample of 100 observations was taken from a large population. The were determined to be 12 and 80 respectively. The standard error of the mear a. 1.20 b. 0.12 c. 8.00 d. 0.80 26. As the sample size decreases, the a. standard deviation of the population decreases b. population mean increases c) standard error of the mean decreases d. standard error of the mean increases 27. As the sample size becomes larger, the sampling distribution of the sample mean approaches a binomial distribution b. Poisson distribution normal distribution d. chi-square distribution 28. A population has a mean of 300 and a standard deviation of 18. A sample of 144 observation taken. The probability that the sample mean will be between 297 to 303 is a. 0.4332 b. 0.8664 e. 0.9544 d. 0.0668 29. A population has a mean of 80 and a standard deviation of 7. A sample of 49 observations wi The probability that the sample mean will be smaller than 82 is a. 0.5228 b. 0.9772 c. 0.4772 d. 0.0228

Explanation / Answer

answer

25) A simple random sample of 100 observations was taken from a large population. The sample mean andthe standard deviation were determined to be 80 and 12 respectively. The standard error of the mean is a. 1.20

28)

P ( -3/18/12) < z < 3 /18/12)) = P ( 2 < z < 2) = .9545

.8664, that would be P( -1.5 < z < 1.5)
Using z = ± 1.5 would be incorrect thing to do in this case.
For the normal distribution:
one standard deviation from the mean accounts for about 68.2% of the set
two standard deviations from the mean account for about 95.5%
and three standard deviations from the mean account for about 99.7%.

29) P(Xmean 82) = P((Xmean - 80)/7/sqrt(49) (82 - 80)/7/sqrt(7)) = P(Z 2) = 0.0228,

1-0.0228=0.9772

answer is 0.9772

answer is 0.8664

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