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Answers to selected problems of Chapter 2
2.8
2.24
a)
The scores of students (out of 100 points) on a very easy exam in which most score perfectly or nearly so, but a few score
very poorly –
skewed to the left because of the few who score poorly
b)
The weekly church contribution for all members of a congregation, in which the three wealthiest members contribute
generously each week –
skewed to the right because of the few wealthy members’ contributions
c)
Time needed to complete a difficult exam (maximum time is 1 hour) –
skewed to the left because most take almost or all
of the whole time, whereas a few finish very quickly
d)
Number of music CD’s (compact discs) owned, for each student in your school –
skewed to the right because of a few
students’ huge CD collections
2.16 Graphing exam scores
:
a)
There are 33 students in the class; the minimum score is 65 and the maximum is 98.
b)
c)
2.32 Resistance to an outlier
:
a)
The median for all three data sets is ten. The values for all three sets of observations are already arranged in numerical
order, and the middle number for each is 10.
b)
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View Full DocumentgG±
g
²
Set 1:
gG
=(8+9+10+11+12)/5=10
Set 2:
gG
=(8+9+10+11+100)/5=27.6
Set 3:
gG
=(8+9+10+11+1000)/5=207.6
c)
As the highest value becomes more and more of an extreme outlier, the median is unaffected, whereas the mean gets
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 Spring '08
 Staff
 Statistics

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