1. A confidence statement based on a probability sample of 1007 American adults
ID: 3069902 • Letter: 1
Question
1. A confidence statement based on a probability sample of 1007 American adults says, “We are 95% confident that between 72% and 78% of all adult Americans believe that the country needs a national health-care system.” The phrase “95% confident” means that
A) We are 95% confident that between 72% and 78% of the 1007 people interviewed would believe that the country needs a national health-care system.
B) If we took many samples, about 95% of the resulting intervals would contain the true value for the percent of all adult Americans who Americans believe that the country needs a national health-care system.
C) The margin of error covers 95% of all responses in the population.
D) 95% of the sample agreed that the country needs a national health-care system.
2. Suppose 600 women were sampled. Gallup asked these 600 women, “What is your favorite Summer Olympic event?” Thirty-five percent said swimming was their favorite. Gallup gave a margin of error for this result. This margin of error is
A) About plus or minus 4 percentage points.
B) less than plus or minus three points because the sample for this question is small.
C) greater than plus or minus three points because the sample for this question is large.
D) About plus or minus 0.2%.
Explanation / Answer
1. As we know, confidence interval will gave the range in which the population parameter will lie.
For A and D, it is mentioned regarding sample and not population hence they are incorrect
And C speaks about Margin of Error, which gives no idea about population parameter hence it is incorrect
For B, it is mentioned that if we took many samples, about 95% of the resulting intervals would contain the true value for the percent of all adult Americans who Americans believe that the country needs a national health-care system. Which means the population parameter will be contained in the resulting intervals.
Hence it is correct answer.
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