CHAPTER 8 Cumulative Review Exercises 435 6. True, False Determine whether the given statements are true or false. a. In a hypothesis test, a very high P-value indicates strong support of the alternative hypothesis. b. The Student t distribution can be used to test a claim about a population mean whenever the sample data are randomly selected from a normally distributed population. c. When using a x2 distribution to test a claim about a population standard deviation, there is a very loose requirement that the sample data are from a population having a normal distribution. d. When testing a claim about a population proportion, the normal distribution can be used regardless of the sample size. e. In a test of the claim that s = 15 for the population of IQ scores of current statistics students, we find that the rightmost critical value is x2 R = 83.298, so the leftmost critical value is x2 L = -83.298. 1.Lightning Deaths Listed below are the numbers of deaths from lightning strikes in the United States each year for a sequence of recent and consecutive years. Find the values of the indicated statistics. 46 51 44 51 43 32 38 48 45 27 34 29 26 28 23 26 28 40 16 20 a. Mean b. Median c. Standard deviation d. Variance e. Range f. What important feature of the data is not revealed from an examination of the statistics, and what tool would be helpful in revealing it? What does a quick examination of the data reveal? 2.Lightning Deaths Refer to the sample data in Cumulative Review Exercise 1. a. What is the level of measurement of the data (nominal, ordinal, interval, ratio)? b. Are the values discrete or continuous? c. Are the data categorical or quantitative? d. Is the sample a simple random sample? 3.Confidence Interval for Lightning Deaths a. Use the sample values given in Cumulative Review Exercise 1 to construct a 99% confidence interval estimate of the population mean. Assume that the population has a normal distribution. b. Write a brief statement that interprets the confidence interval. c. Is the confidence interval estimate of m good for predicting the number of lightning deaths 10 years into the future? Why or why not? 4.Hypothesis Test for Lightning Deaths Refer to the sample data given in Cumulative Review Exercise 1 and consider those data to be a random sample of annual lightning deaths from recent years. Use those data with a 0.01 significance level to test the claim that the mean number of annual lightning deaths is less than the mean of 72.6 deaths from the 1980s. If the mean is now lower than in the past, identify one of the several factors that could explain the decline. Cumulative Review Exercises
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