The head librarian at the Library of Congress has asked her assistant for an interval estimate of the mean number of books checked out each day. The assistant provides the following interval estimate: from 740 to 920 books per day. If the head librarian knows that the population standard deviation is 150 books checked out per day, approximately how large a sample did her assistant use to determine the interval estimate?
A) 12
B) 2
C) 3
D) It cannot be determined from the information given.
Q. 2When determining the sample size necessary for estimating the true population mean, which factor is not considered when sampling with replacement?
A) the allowable or tolerable sampling error B) the level of confidence desired in the estimate
C) the population standard deviation D) the population size
Q. 3A confidence interval was used to estimate the proportion of statistics students who are females. A random sample of 72 statistics students generated the following 90 confidence interval: (0.438, 0.642). Based on the interval above, is the population proportion of females equal to 0.60?
A) No, and we are 90 sure of it.
B) No. The proportion is 54.17.
C) Yes, and we are 90 sure of it.
D) Maybe. 0.60 is a believable value of the population proportion based on the information above.
Q. 4When determining the sample size for a proportion for a given level of confidence and sampling error, the closer to 0.50 that is estimated to be, the sample size required
A) is smaller. B) is not affected.
C) is larger. D) can be smaller, larger or unaffected.
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