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Chapter 8: Q. 9.67 (page 370)
Determine the sufficient evidence to reject the null hypothesis in favor of alternative hypothesis.
Two test failed
(a) z= -1.66 (b) z= 0.52
(a) The P-value is 0.09691
(b) The P-value is 0.60306
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Testing Claims About Proportions. In Exercises 9鈥�32, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-value, or critical value(s), then state the conclusion about the null hypothesis, as well as the final conclusion that addresses the original claim. Use the P-value method unless your instructor specifies otherwise. Use the normal distribution as an approximation to the binomial distribution, as described in Part 1 of this section.
Medical Malpractice In a study of 1228 randomly selected medical malpractice lawsuits, it was found that 856 of them were dropped or dismissed (based on data from the Physicians Insurers Association of America). Use a 0.01 significance level to test the claim that most medical malpractice lawsuits are dropped or dismissed. Should this be comforting to physicians?
Testing Hypotheses. In Exercises 13鈥�24, assume that a simple random sample has been selected and test the given claim. Unless specified by your instructor, use either the P-value method or the critical value method for testing hypotheses. Identify the null and alternative hypotheses, test statistic, P-value (or range of P-values), or critical value(s), and state the final conclusion that addresses the original claim.
Speed Dating Data Set 18 鈥淪peed Dating鈥� in Appendix B includes 鈥渁ttractive鈥� ratings of male dates made by the female dates. The summary statistics are n = 199, x = 6.19, s = 1.99. Use a 0.01 significance level to test the claim that the population mean of such ratings is less than 7.00.
Testing Claims About Proportions. In Exercises 9鈥�32, test the given claim. Identify the null hypothesis, alternative hypothesis, test statistic, P-value, or critical value(s), then state the conclusion about the null hypothesis, as well as the final conclusion that addresses the original claim. Use the P-value method unless your instructor specifies otherwise. Use the normal distribution as an approximation to the binomial distribution, as described in Part 1 of this section.
Store Checkout-Scanner Accuracy In a study of store checkout-scanners, 1234 items were checked for pricing accuracy; 20 checked items were found to be overcharges, and 1214 checked items were not overcharges (based on data from 鈥淯PC Scanner Pricing Systems: Are They Accurate?鈥� by Goodstein, Journal of Marketing, Vol. 58). Use a 0.05 significance level to test the claim that with scanners, 1% of sales are overcharges. (Before scanners were used, the overcharge rate was estimated to be about 1%.) Based on these results, do scanners appear to help consumers avoid overcharges?
Identifying and . In Exercises 5鈥�8, do the following:
a. Express the original claim in symbolic form.
b. Identify the null and alternative hypotheses.
Pulse Rates Claim: The mean pulse rate (in beats per minute, or bpm) of adult males is equal to 69 bpm. For the random sample of 153 adult males in Data Set 1 鈥淏ody Data鈥� in Appendix B, the mean pulse rate is 69.6 bpm and the standard deviation is 11.3 bpm.
Finding Critical t Values When finding critical values, we often need significance levels other than those available in Table A-3. Some computer programs approximate critical t values by calculating where df = n-1, e = 2.718, , and z is the critical z score. Use this approximation to find the critical t score for Exercise 12 鈥淭ornadoes,鈥� using a significance level of 0.05. Compare the results to the critical t score of 1.648 found from technology. Does this approximation appear to work reasonably well?
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