The carbon monoxide in cigarettes is thought to be hazardous to the fetus of a pregnant woman who smokes. In a study of this hypothesis, blood was drawn from pregnant women before and after smoking a cigarette. Measurements were made of the percent of blood hemoglobin bound to carbon monoxide as carboxyhemoglobin (COHb).The results for 10 women are shown in the table.

(a) Calculate the mean and SD of the increase in COHb.
(b) Calculate the mean COHb before and the mean after. Is the mean increase equal to the increase in means?
(c) Determine the median increase in COHb.
(d) Repeat part (c) for the before measurements and for the after measurements. Is the median increase equal to the increase in medians?

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Blood COHb (%) Subject Before After Increase 1.2 1.4 1.5 2.4 3.6 0.5 2.0 1.5 6.4 2.6 3.5 3.9 2.2 5,5 4.0 5,0 5.8 6.0 6.4 5.0 4.2 5.2 3.5 3.2 3.5 10 1.7