Consider a poll that reported that % of people from a certain region have tried marijuana. The survey polled adults from the region and had a margin of error of plus or minus percentage points with a % level of confidence. Complete parts (a) through (c) below.
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For the purpose of providing a comprehensive step-by-step solution, I'll assume some values. Let's say 40% of people from a certain region have tried marijuana, the survey polled 1000 adults, with a margin of error of plus or minus 5 percentage points, and a 95% Show more…
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The Gallup poll reported that $45 \%$ of Americans have tried marijuana. This was based on a survey of 1021 Americans and had a margin of error of plus or minus 5 percentage points with a $95 \%$ level of confidence. a. State the survey results in confidence interval form and interpret the interval. b. If the Gallup Poll was to conduct 100 such surveys of 1021 Americans, how many of them would result in confidence intervals that did not include the true population proportion? c. Suppose a student wrote this interpretation of the interval: "We are $95 \%$ confident that the percentage of Americans who have tried marijuana is between $40 \%$ and $50 \%$." What, if anything, is incorrect in this interpretation?
Prabhakar K.
Consider a poll that reported that 50% of people from a certain region have tried marijuana. The survey polled 1,031 adults from the region and had a margin of error of plus or minus 3 percentage points with a 95% level of confidence. Complete parts (a) through (c) below. The confidence interval of the survey results is ( , ). (Round to two decimal places as needed.) Interpret the interval. Choose the correct answer below. A. We are 95% confident that the percentage of people in the region who have tried marijuana is within the confidence interval. B. There is a 95% chance that the percentage of people in the region who have tried marijuana is within the confidence interval. C. The confidence interval will contain the percentage of people in the region who have tried marijuana 95% of the time. D. 95% of the 1,031 people from the region that were polled fell within the confidence interval. b. If the polling company was to conduct 100 such surveys of 1,031 people from the region, how many of them would result in confidence intervals that did not include the true population proportion? Approximately of the confidence intervals would not include the true population proportion. c. Suppose a student wrote this interpretation of the interval: "We are 95% confident that the percentage of people from this region who have tried marijuana is within the confidence interval." What, if anything, is incorrect in this interpretation? A. This interpretation is incorrect because the confidence level represents how often the confidence interval will contain the correct population proportion. B. This interpretation is incorrect because the confidence level states the probability that the sample proportion is within the confidence interval. C. This interpretation is incorrect because a confidence interval is about a population not a sample. D. There is nothing wrong with this interpretation.
Sri K.
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