A scrap metal dealer claims that the mean of his cash sales is “no more than $80,” but an Internal Revenue Service agent believes the dealer is untruthful. Observing a sample of 20 cash customers, the agent finds the mean purchase to be $91, with a standard deviation of $21. Assuming the population is approximately normally distributed, and using the 0.05 level of significance, is the agent’s suspicion confirmed?
Answer to relevant QuestionsDuring 2008, college work-study students earned a mean of $1478. Assume that a sample consisting of 45 of the work-study students at a large university was found to have earned a mean of $1503 during that year, with a ...Using the sample results in Exercise 10.52, construct and interpret the 95% confidence interval for the population mean. Is the hypothesized population mean (93 seconds) within the interval? Given the presence or absence of ...For a simple random sample, n = 200 and p = 0.34. At the 0.01 level, test H0: π = 0.40 versus H1: ≠ 0.40. Heritage Union has said that 66% of U.S. adults have purchased life insurance. Suppose that for a random sample of 50 adults from a given U.S. city, a researcher finds that only 56% of them have purchased life insurance. At ...According to the National Collegiate Athletic Association (NCAA), 41% of male basketball players graduate within 6 years of enrolling in their college or university, compared to 56% for the student body as a whole. Assume ...
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