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Unformatted text preview: Exam 1 for Math 1680
Name: Date; Zfﬁﬁi/ﬁg Directions: Answer as many of the following questions as yea
can. Box your ﬁnal answer! If I can’t find your answer, I won’t
grade it. Partial credit may be given for work shown, but a wrong answer without supporting work or justifications will receive no credit. A complimentary normal table has been provided at the back of your test. Feel free to tear it off and use it. Good Luck! '1; W
Total Score: t @ /150 Question 1 (35 points): 3. (Hypothetical) An engineer knows from prior records that the
distribution of weight on an elevator in an apartment building for each lift last year is approximately normal, with an average weight of 1000 lbs and a standard deviation of
150 lbs. :1) (10 points): What percentage of the time did the elevator lift more than 1100
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E » i!” 3’" "do m ’ Question 2 (20 points): (AP) An increasing number of city shooting victims have had
previous brushes with the law, according to a new study by city criminologists. The report from researchers with the Philadelphia Adult Probation and i’arole
Department found that 24 percent of shooting victims in 2006 had pending criminal court
cases against them at the time they were shot. In 2002, the ﬁgure was 18 percent. Thirty percent of gunhomicide victims last year had pending criminal cases at the time
they were killed, up from 20 percent in 2003, according to the report. The analysts did not attempt to categorize the pending charges against the victims to
determine whether they were minor offenses or violent acts. However, researchers found
that gun violence is larger conﬁned to the city's poorest areas. a) (19 points) Was this study a controlied experiment or an observational study? Justify
your answer! iii“ ‘5 X ft 1)) (5 points) identify the control and treatment groups. MT. i , , _ 4 , .r .". IE, fig/E ihc Vfo’mfit’ux JP filaa‘ll'iy ‘ (fiﬁfwmiif Ibraifmj . Hqu ZOﬂé (%}pgt§;h€awi) i0 ff'a‘iliofiliis affix? 1mg but!) 51);} wiry Vlnﬁrﬂ‘M “255;? {may
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income in the US in 1973: $0  $5,000
25 — '50 lit—:57
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incomes, should he use the average or the median as a central tendency measure? E wk 71]“ (Mam: file om’waflﬁiaa/afam "til .0 j 
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ﬁe Gd”? mum; ‘an m: (M if) Question 4 (30 points): In a college statistics class, the comparison of height and weight
for students results in the following summary. Average weight: 160 pounds SD for weight: 25 pounds
Average height: 69 inches SD for height: 4 inches
Correlation (r): 0.65 a) (10 points) Predict and give the RMS error for the height of a student weighing mum pounds' » {7 w e Wear“! 0’ 3 0%
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coefﬁcient for each pair of data sets. If you use changes of scale for your calculations,
make sure you state What the changes of scale are! Lit“+ ‘f‘ttili? : 112:“ a)(15 points) A; z 5 “g”
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 Fall '08
 Patton
 Statistics, Mass, Percentage point, Human height, Confounding

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