(1 point) For each problem, select the best response. (a) An engineer designs an improved light bulb. The previous desig

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1 Point For Each Problem Select The Best Response A An Engineer Designs An Improved Light Bulb The Previous Desig 1 (82.53 KiB) Viewed 74 times

(1 point) For each problem, select the best response. (a) An engineer designs an improved light bulb. The previous design had an average lifetime of 1200 hours. The new bulb had a lifetime of 1200.2 hours, using a sample of 40,000 bulbs. Although the difference is quite small, the effect was statistically significant. The explanation is Ha A. that the mean of 1200 is large. B. that new designs typically have more variability than standard designs. C. that the sample size is very large. D. all of the above. (b) The nicotine content in cigarettes of a certain brand is normally distributed with mean (in milligrams) y and standard deviation 6 = 0.1. The brand advertises that the mean nicotine content of their cigarettes is 1.5, but you believe that the mean nicotine content is actually higher than advertised. To explore this, you test the hypotheses H: 4 = 1.5. H. : > 1.5 and you obtain a P-value of 0.052. Which of the following is true? A. You have failed to obtain any evidence for B. This should be viewed as a pilot study and the data suggests that further investigation of the hypotheses will not be fruitful at the a = 0.05 significance level. C. At the a = 0.05 significance level, you have proven that He is true. OD. There is some evidence against Ho, and a study using a larger sample size may be worthwhile. (c) Does 30 minutes of aerobic exercise each day provide significant improvement in mental performance? To investigate this issue, a researcher conducted a study with 150 adult subjects who performed aerobic exercise each day for a period of six months. At the end of the study, 200 variables related to the mental performance of the subjects were measured on each subject and the means compared to known means for these variables in the population of all adults. Nine of these variables were significantly better in the sense of statistical significance) at the a = 0.05 level for the group that performed 30 minutes of aerobic exercise each day as compared to the population as a whole, and one variable was significantly better at the a = 0.01 level for the group that performed 30 minutes of aerobic exercise each day as compared to the population as a whole. It would be correct to conclude