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2.5
(a) The fivenumber summary is Min = 23,040, Q1=30,315, M=31,975, Q3=32,710, Max=33,650.
(b) Note the distances between the numbers in the fivenumber summary: In order, the gaps are 7275,
1660, 735, and 940 pounds. That the first two gaps are larger gives some indication of the left skew.
2.9
(a) x_mean=32.4/6=5.4mg of phosphate per deciliter of blood.
(b) The standard deviation is s=sqrt(2.06/5)=0.6419mg/dl.
2.11
(a) Not appropriate : the distribution of percents of college graduates has a hight outlier.
(b) x_mean and s are fine: The Iowa Test score distribution is quite symmetric and has no outliers.
(b) Not appropriate : The wood breakingstrength distribution is strongly skewed.
2.25
(a) The mean will be greater than the median because of the right skew. We find that x_mean=251.9
and M=236 doctors per 100,000 people.
(b) Outliers have a greater effect on the mean, so removing D.C. should change x_mean more than M.
Indeed, we find that x_mean^* (^* means a superscript)=243.26 and M^*=234.5 doctors per 100,000
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 Spring '10
 Kushner
 Statistics

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