Chapter_10_-_Recommended_Problems_-_Answers

Chapter_10_-_Recommended_Problems_-_Answers - 10.2 (a) t...

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10.2 (a) ± ² ³ ´´ 8959 . 3 STAT t (b) d.f. = 21 (c) Decision rule: d.f. = 21. If t STAT > 2.5177, reject H 0 . (d) Decision: Since t = 3.8959 is greater than the critical bound of 2.5177, reject H 0 . There is enough evidence to conclude that the first population mean is larger than the second population mean. 10.3 Assume that you are sampling from two independent normal distributions having equal variances. 10.4 d.f. = 21, µ ² · ³ ´¸¹º»¼ , 95% confidence interval is between 2.7296 and 12.2704. 10.5 V=17.4639 and hence df = 17 10.6 1779 . 4 STAT t and critical value ½´¸¾»¾´ . Decision: Since t STAT = 4.1779 is larger than the upper critical bounds of 2.8982, reject H 0 . There is evidence of a difference in the means of the two populations. 10.7 (a) df = 48, ¿ ³ ¹¸¹À , µ Á ³ ½´¸¹Â¹¼ µ ÃÄÅÄ ³ ¹¸Æ¹¼Â Decision: Since t STAT = 0.4061 is between the critical bounds of 2.0106, do not reject H 0 . There is no evidence of a difference in the mean life of bulbs produced by the two types of machines at the 0.05 level of significance. (b) V = 45, ¿ ³ ¹¸¹À , µ Á ³ ½´¸¹ÂÆ Decision: Since t STAT = 0.4061 is between the critical bounds of 2.0141, do not reject H 0 . There is no evidence of a difference in the mean life of bulbs produced by the two types of machines at the 0.05 level of significance. 10.9 Assuming that the variance of the weight loss of the low-fat diet and low-carb diet are the same, the appropriate test to perform is the pooled-variance t test. (a) H 0 : 1 2 H 1 : 1 2 (b) A Type I error is committed when one concludes that there is a difference in mean weight loss between the two diets when there is not significant difference. (c) A Type II error is committed when one concludes that there is not significant difference in mean weight loss between the two diets when there is indeed significant difference.
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Chapter_10_-_Recommended_Problems_-_Answers - 10.2 (a) t...

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