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5.4 Unexpected expense. In a random sample 765 adults in the United States, 322 say they could not

cover a $400 unexpected expense without borrowing money or going into debt.

(a) What population is under consideration in the data set?

(b) What parameter is being estimated?

(c) What is the point estimate for the parameter?

(d) What is the name of the statistic can we use to measure the uncertainty of the point estimate?

(e) Compute the value from part (d) for this context.

(f) A cable news pundit thinks the value is actually 50%. Should she be surprised by the data?

(g) Suppose the true population value was found to be 40%. If we use this proportion to recompute the

value in part (e) using p = 0:4 instead of ^p, does the resulting value change much?

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5.8 Twitter users and news, Part I. A poll conducted in 2013 found that 52% of U.S. adult Twitter users get

at least some news on Twitter.12. The standard error for this estimate was 2.4%, and a normal distribution

may be used to model the sample proportion. Construct a 99% confidence interval for the fraction of U.S.

adult Twitter users who get some news on Twitter, and interpret the confidence interval in context.