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Chapter 7: Q 38. (page 462)
More workers What sample size would be required to reduce the standard deviation of the sampling distribution to one-third the value you found in Exercise 36(b)? Justify your answer.
Sample size is.
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Cholesterol Suppose that the blood cholesterol level of all men aged 20 to 34 follows the Normal distribution with mean milligrams per deciliter (mg/dl) and standard deviation .
a. Choose an SRS of 100 men from this population. Describe the sampling distribution of .
b. Find the probability that estimates within . (This is the probability that takes a value between 185 and
c. Choose an SRS of 1000 men from this population. Now what is the probability that falls within of ? In what sense is the larger sample "better"?
Why is it important to check the 10 % condition before calculating probabilities involving localid="1654670795605">
a. To reduce the variability of the sampling distribution of
b. To ensure that the distribution of is approximately Normal
c. To ensure that we can generalize the results to a larger population
d. To ensure that will be an unbiased estimator of
e. To ensure that the observations in the sample are close to independent
According to the U.S. Census, the proportion of adults in a certain county who owned their own home was 0.71. An SRS of 100 adults in a certain section of the county found that 65 owned their home. Which one of the following represents the approximate probability of obtaining a sample of 100 adults in which 65 or fewer own their home, assuming that this section of the county has the same overall proportion of adults who own their home as does the entire county?
a.
b.
c.
d.
e.
A study of rush-hour traffic in San Francisco counts the number of people in each car entering a freeway at a suburban interchange. Suppose that this count has mean 1.6 and standard deviation 0.75 in the population of all cars that enter at this interchange during rush hour.
a. Without doing any calculations, explain which event is more likely:
b. Explain why you cannot use a Normal distribution to calculate the probability of the first event in part (a).
c. Calculate the probability of the second event in part (a).
On one episode of his show, a radio show host encouraged his listeners to visit his website and vote in a poll about proposed tax increases. Of the 4821 people who vote, 4277 are against the proposed increases. To which of the following populations should the results of this poll be generalized?
a. All people who have ever listened to this show
b. All people who listened to this episode of the show
c. All people who visited the show host's website
d. All people who voted in the poll
e. All people who voted against the proposed increases
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