Homework5 - c Find a 99 confidence interval for the true...

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Homework 5 1. Consumer Reports found that a sample of 5 Toyota Yaris cars averaged 34 mpg, with a known standard deviation of 3 mpg. a. Find a 90% confidence interval for the true mileage of the Toyota Yaris. b. Interpret the interval in (a). 2. Say we repeat the mileage study from problem 1, but with 20 cars. We got an average of 35 mpg. a. Find a 90% confidence interval for the true mileage for this new sample. b. Compare the interval in (a) to that found in problem 1. 3. A non-scientific survey of 486 bloggers revealed that 370 of them do not limit access to their blogs in any way. a. Find a 95% confidence interval for the true proportion of all bloggers who do not limit access to their blogs. b. Interpret the interval in (a).
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Unformatted text preview: c. Find a 99% confidence interval for the true proportion of all bloggers who do not limit access to their blogs. d. Compare the intervals in (a) and (c). e. Find a 99% confidence interval for the true proportion of all bloggers that do limit access to their blogs. f. Compare the intervals in (c) and (e). 4. We are interested in estimating, with 80% confidence, the true proportion of bloggers who provide some variant of their real name, within 3%. a. How many bloggers would we need to survey in order to accomplish this? b. Say we suspect, based on a pilot study, that the proportion of bloggers that reveal some variant of their true identity is around 20%. Now how many bloggers would we need to survey?...
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