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16) The standard error of the sample mean is equal to 5 when n=25. If the sample size increases by a factor of four, how will the standard error

16) The standard error of the sample mean is equal to 5 when n=25. If the sample size increases by a factor of four, how will the standard error change?
A. It will double
C. It will be cut to ¼ of 5
D. It will be cut in half

17) Which of the following statements is consistent with the Central Limit Theorem?
A. When µ and s are known, the population will be approximately normally distributed.
B. Means of samples of n=30 from an exponential distribution will be approximately normally distributed.
C. When we know s, the variation in the sample means will be equal to that of the population.
D. If a population has µ and s, a sample from that population will be normally distributed if the sample size is large enough.

18) For a sample size of 1, the sampling distribution of the mean will be normally distributed
A. regardless of the shape of the population.
B. only if the population is normally distributed.
C. only if the population values are larger than 30.
D. only if the shape of the population is positively skewed.

19) A random sample of 25 observations is selected from a normally distributed population. The sample variance is 10. In the 95% confidence interval for the population variance, the upper limit will be:
A. 17.110.
B. 19.353.
C. 17.331.
D. 6.097.

20)
A study of 200 insomniacs paid for by the Serta Mattress Company found that the average insomniac counted 350 sheep before falling asleep, with a standard deviation of 120. An insomniac is a person who has difficulty falling asleep. Some useful numbers might be:

=NORMSINV(0.89)
1.2265

=NORMSINV(0.945)
1.5982

=TINV(0.89,199)
0.1385

=TINV(0.11,199)
1.6053

=TINV(0.055,199)
1.9302

Out of the 200 insomniacs, 98 reported regularly watching The Late Show with David Letterman before they began to count sheep. Calculate the margin of error for a 78% confidence interval of the true proportion of insomniacs who regularly watch David Letterman before counting sheep.
A. 0.043
B. 0.164
C. 0.136
D. 0.056

21)
Construct a 95% confidence interval estimate for the difference between the means of two normally distributed populations, where the unknown population variances are assumed not to be equal. Summary statistics computed from two independent samples are as follows:

The upper confidence limit is:

A. 19.123.
B. 5.788.
C. 24.911.
D. 28.212.

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