Statistics in a Modern World 800
Solutions to Exam 2

 (iii) skewed right/high outliers
 (iv) 23: mean greater than median (outliers pull mean up) but 32 would
be way too high
 (iii) 6 is the typical distance of those values from their mean;
.06 and .6 would be way too low and 60 would be way too high
 (iii) can't tell for sure, because minimum is anywhere from 14 to 16 and
maximum is anywhere from 34 to 36

 (iv) multiple boxplots (for values of one measurement variable compared
for five categorical groups)
 (ii) piechart (for one categorical variable)
 (iii) scatterplot (for two measurement variables)
 (i) 1 because it is a perfect negative relationship

 z=(712)/2=2.5; the proportion below is .005, according to Table
 shortest 1% have z=2.33, observed value = 122.33(2)=7.34
 (d) [(a) not appropriate because heights level off before 20, and the
relationship is not at all linear; (b) not appropriate because living situation
is categorical]

 (i) long term upward trend: fares are increasing
 .60(189.5)/82.4=$1.38
 (ii)$2.50 is too high because $1.38 would have kept pace with inflation
 92+.0468(2004)=1.79
 +1 because it is strong and positive

 (7)
 5 (slower metaolism is a common cause)
 1 (TV is a direct cause of obesity
 3 (TV is a contributing cause to obesity)
 2 (causation in the opposite direction, with obesity causing children
to watch TV)
 6 (TV and weight both increasing over time)
 4 (socioeconomic status is a confounding variable)

 (i)males: 61/120=.51 as opposed to 89/240=.37 for females
 calculate (column total * row total)/table total: 100, 50, 140, 70
 1.2, 2.4, .9, 1.7
 1.2+2.4+.9+1.7=6.2
 (ii) 6.2 > 3.84, so we have convincing statistical evidence of a
relationship
 we cannot claim to know the reason for the relationship as (iii) suggests.
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