The birth weights(in grams) are given for babies born to 22 mothers who smoked during their pregnancy and to 35 mothers who did not smoke. Seven pounds is about 3200 grams.
X Infant Birth Weights Smoke? No Yes 3612 3229 3691 1984 3512 2961 3357 2968 3612 2949 3080 5264 3592 3642 3080 3655 3406 3576 4368 2963 3733 2296 3024 1008 2476 847 4872 2825 3450 2688 4181 4018 3640 2688 4256 1929 4312 3108 4760 2056 2940 3329 4047 2996 4172 2952 2688 4152 3936 2534 2744 3864 2966 3668 3607 3820 3542a. Compare the means and standard deviations in context. The mean birth weight for babies born to non-smoking mothers is 3589.89 grams. The mean birth weight for babies born to smoking mothers is 2862.68 grams. The mean birth weight for babies born to non-smoking mothers is greater than the mean birth weight for babies born to smoking mothers. (Round to two decimal places as needed.) The standard deviation of birth weight for babies born to non-smoking mothers is 597.65 grams. The standard deviation of birth weight for babies born to smoking mothers is 963.47 grams. The standard deviation of birth weight for babies born to non-smoking mothers is less than the standard deviation of birth weight for babies born to smoking mothers. (Round to two decimal places as needed.) b. Remove the outlier of 847 grams for the smoking mothers, make the comparison again, and comment on the eect of removing the outlier. With the outlier removed, the mean birth weight for babies born to smoking mothers is 2958.67 grams. The mean birth weight for babies born to non-smoking mothers is 3589.89 grams. The mean birth weight for babies born to nonsmoking mothers is greater than the mean birth weight for babies born to smoking mothers. (Round to two decimal places as needed.) With the outlier removed, the standard deviation of birth weight for babies born to non-smoking mothers is 597.65 grams. The standard deviation of birth weight for babies born to smoking mothers is 872.85 grams. The standard deviation of birth weight for babies born to nonsmoking mothers is less than the standard deviation of birth weight for babies born to smoking mothers. Identify the effect of removing the outlier on the standard deviation for birth weight of babies born to smoking mothers. 0 A. By removing the outlier, the standard deviation decreases. Removing the outlier eliminates an addend from the calculation, which necessarily decreases variation. O B. By removing the outlier, the standard deviation increases. Each observation will have a greater impact on the standard deviation, so the standard deviation must be greater than or equal to its prior value. O C. By removing the outlier, the standard deviation decreases. Since this value is farthest from the mean, its large contribution to the standard deviation would be removed. 0 D. By removing the outlier, the standard deviation increases. Removing the outlier decreases the sample size, leading to a greater standard deviation
