EBook Problems Estim Proportion

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Revision as of 21:22, 28 November 2008

EBook Problems Set - Estimating a Population Proportion

Problem 1

A 1996 poll of 1,200 African American adults found that 708 think that the American dream has become impossible to achieve. The New Yorker magazine editors want to estimate the proportion of all African American adults who feel this way. Which of the following is an approximate 90% confidence interval for the proportion of all African American adults who feel this way?

• Choose one answer.

(a) (.56, .62)

(b) (.57, .61)

(c) Can't be calculated because the population size is too small.

(d) Can't be calculated because the sample size is too small.

Problem 2

True or False: In a well-designed sample survey like the Current Population Survey, the observed sample percentage (e.g, percentage unemployed) is equal to the population percentage. Thus, it is appropriate to just report the sample percentage, without any measure of accuracy (i.e. without the margin of error).

• Choose one answer.

(a) True

(b) False

Problem 3

The BBC news does a story and at one point the reporter says: "A polling agency reports that the percentage of the American public who agree we should spend more money on the mental health of the war veterans is 42% +/- 3%."

• Choose one answer.

(a) The probability that the American public agree that we should spend more money on the mental health of the war veterans is between 39% to 42%.

(b) The percentage of the American public who agree that we should spend more money on the mental health of the war veterans is between 39% to 45%.

(c) We are 95% confident that the percentage of the American public who agree that we should spend more money on the mental health of the war veterans is between 39% to 45%.

(d) The percentage of the American public who agree that we should spend more money on the mental health of the war veterans is 42%.

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