Attempt 3 In a study of exhaust emissions from school buses, the pollution intake by passengers was determined for a sample of nine school buses used in the Southern California Air Basin. The pollution intake is the amount of exhaust emissions, in grams per person, that would be inhaled while traveling on the bus during its usual 18-mile trip on congested freeways from South Central LA to a magnet school in West LA. (As a reference, the average intake of motor emissions of carbon monoxide in the LA area is estimated to be about 0.000046 grams per person.) The amounts for the nine buses when driven with the windows open are given. 1.15 0.33 0.40 0.33 1.35 0.38 0.25 0.40 0.35 To access the complete data set, click the link for your preferred software format: Excel Minitab JMP SPSS TI R Mac-TXT PC-TXT CSV CrunchIt! (a) Make a stemplot. Are there outliers or strong skewness that would forbid use of the t procedures? The stemplot suggests the presence of outliers. The sample is small and the stemplot is skewed, so the use of t procedures is not appropriate. O The stemplot does not indicate the presence of outliers. The sample is small and the stemplot is skewed, so the use of t procedures is not appropriate. O The stemplot does not indicate the presence of outliers. The sample is small but the stemplot is not skewed, so the use of t procedures is appropriate. O The stemplot suggests the presence of outliers. The sample is small but the stemplot is not skewed, so the use of t procedures is appropriate. Publisher: W.H. Freem Question Source: Moore, The Basic Practice Of Statistics, 8e (b) A goòd way to judge the effect of outliers is to do your analysis twice, once with the outliers and a second time without them. Give two 90% confidence intervals, one with all the data and one with the outliers removed, for the mean pollution intake all school buses used in the Southern California Air Basin that travel the route investigated in the study. Use among Table C or the software of your choice for these calculations. (Enter your answers rounded to three decimal places.) lower bound all data upper bound all data lower bound outliers removed upper bound outliers removed (c) Compare the two intervals in part (b). What is the most important effect of removing the outliers? simplification of calculations Oincreasing of confidence interval O reducing margins of error Publisher: W.H. Freen Question Source: Moore, The Basic Practice Of Statistics, 8e