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STAT 2040
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Jeremy Balka
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Statistics

STAT 2040

Jeremy Balka

Summer

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STAT*2040 W12
Test 1 (White Version)
February 15 2012
This page is included to satisfy the U of G’s privacy policy. Please ﬁll out your ﬁrst and last names on
this page, but not your ID number or any other information.
Last Name:
First Name:
On the next page, please ﬁll out your name and ID number. University of Guelph
Department of Mathematics and Statistics
STAT*2040
Statistics I
Test 1 (White version)
February 15 2012
Examiner: Jeremy Balka
This exam is 70 minutes in duration
Name:
ID:
Signature:
Please read the instructions:
1. Fill out your name and ID number above.
2. When the examination starts, make sure your question paper is complete. You should have 22
multiple choice questions , along with a formula sheet and standard normal tables. The ﬁrst
question is just a bookkeeping question, and does not count for marks, but please ﬁll it in to ensure
your exam is properly graded.
3. Do all rough work on this paper.
4. You are allowed to bring in a calculator, and pens and pencils.
5. There is only one correct answer for each question. Fill in only one bubble for each question.
6. Fill out the computer answer sheet in pencil as you go. There will be no extra time given at the
end of the exam to ﬁll in the sheet.
7. The answers given in the exam are often rounded versions of the correct answer. Choose the
closest value. 1. The colour of the ﬁrst page of this examination booklet (the cover sheet) is:
(a) White
(b) Yellow
2. A study investigated the eﬀect of a regular dose of aspirin on the risk of strokes. Physicians
randomly assigned approximately 5,000 volunteers to a group that took an aspirin every second
day, and 5,000 to a control group that took a placebo instead. The volunteers were followed
for several years, and researchers compared the rate of strokes in the two groups. Consider the
following statements.
I. This is an experiment, not an observational study.
II. The response variable is aspirin use.
III. This type of study cannot possibly yield evidence of a causal link between aspirin use and
rate of strokes.
Which of these statements are true?
(a) Just I.
(b) I and III.
(c) II and III.
(d) All of them.
(e) None of them.
3. Consider the following sample of 4 observations: ▯8;12;16;31.
What is the value of the sample variance?
(a) 11
(b) 16
(c) 29
(d) 112
(e) 258
3 of 9 4. If all observations in a data set have 10 added to them, how many of the following quantities would
change in value?
▯, s, Q1, IQR, 10th percentile.
(a) 1
(b) 2
(c) 3
(d) 4
(e) 5
5. Which one of the following statements is true?
(a) For right-skewed distributions, the median is greater than the mean.
(b) For mound-shaped distributions, approximately 50% of observations lie within 5 standard
deviations of the mean.
(c) For any distribution, the interquartile range is equal to 50.
(d) If the range of a data set is equal to 0, the variance and IQR will also equal 0.
(e) None of the above.
6. A human resources administrator in a large company is interested in estimating the average age
of new hires. The administrator looks at an alphabetical list of 200 new hires, and picks the ﬁrst
30 names on the list. They ﬁnd the average age of these 30 people is 28.2. Consider the following
statements.
I. This is an experiment, not an observational study.
II. The number 28.2 is a statistic, not a parameter.
III. The 30 people represent a simple random sample from the population of interest.
Which of these statements are true?
(a) Just II.
(b) I and II.
(c) I and III.
(d) II and III.
(e) None of them.
4 of 9 7. A new mother and father bring their 2 month old baby in to see their doctor for a check-up. The
doctor measures the baby’s length in centimetres, and tells the parents that in terms of length of
babies that age, their baby’s z-score is ▯2:0. Which one of the following statements is true?
(a) The units of the z-score are centimetres.
(b) The baby’s length is 2 centimetres less than the mean length of babies that age.
(c) The baby’s length is greater than 50% of babies that age.
(d) The baby’s length is 2 standard deviations less than the mean length of babies of that age.
8. Is there a relationship between fatty ﬁsh consumption and the rate of prostate cancer? A study
followed 6272 Swedish men for 30 years. They were categorized according to their ﬁsh consumption,
and to whether they developed prostate cancer. The following table summarizes the results.
Fish consumption
Never/seldom Small Moderate Large
Prostate cancer 14 201 209 42
No prostate cancer 110 2420 2769 507
If one of these 6272 men is randomly selected, what is the probability their ﬁsh consumption was
large or moderate, give

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