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TAKE HOME EXAM
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6.
When a 99% confidence interval is calculated instead of a 95% confidence interval with n
being the same, the maximum error of estimate will be:
(A) Smaller
(B) Larger
(C) The same
(D) It cannot be
determined
7.
The best point estimate of the population mean is:
(A) sample mean
(B) sample median
(C) sample mode
8.
(D) sample midrange
DO YOU DRINK THE CEREAL MILK?
A USA TODAY poll asked a random sample of 1012 U.S. adults what they do with the milk in
the bowl after they have eaten the cereal. Of the respondents, 67% said that they drink it.
Suppose that 70% of U.S. adults actually drink the cereal milk.
(a) Find the mean and standard deviation of the proportion of the sample (p-hat) that say they
drink the cereal milk.
(b) Show how you would check that you can use the normal approximation for the distribution
of p-hat.
(c) Find the probability of obtaining a sample of 1012 adults in which 67% or fewer say they
drink the cereal milk.
9.
What is the difference between a point estimate and an interval estimate of a parameter? Which is
better? Why?
10. The growing seasons for a random sample of 35 U.S. cities were recorded, yielding a sample mean
of 190.7 days and a sample standard deviation of 54.2 days. Estimate the true mean population of
the growing season with 95% confidence.
11. Sherdale is interested in estimating the average monthly salary of sports reporters in a large city. He
wants to be 90% confident that his estimate is correct. If the standard deviation is $1100, how large
a sample is needed to get the desired information and to be accurate within $150.
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