MAT 2378
Midterm
version A
26 October, 2009
Professor: Pawel Lorek
Time: 70 minutes
Student Number:
Family Name:
First Name:
This is a closed book examination.
Only nonprogrammable and nongraphic calculators are permitted.
Record your answer to each question in the table below.
NOTE: At the end of the examination, hand in only this page.
Question
Answer
1
2
3
4
5
6
7
8
9
10
1
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Q
1.
In a study of the lizard
Sceloporus occidentalis
, biologists measured the distance (m) run in two minutes for
each of 15 animals. The results were as follows:
32.9 32.9 34.0 34.8 37.5 42.1 45.5 45.5
18.4 22.2 24.5 26.4 27.5 28.7 30.6
The median and the first quartile are, respectively, :
(a)
32.9; 26.4;
(b)
32.9; 27.5;
(c)
33.1; 26.95;
(d)
33.1; 26.4
(e)
none of the preceding
Q
2.
Suppose a certain drug test is 99% sensitive and 99% specific, that is, the test will correctly identify a drug user
as testing positive 99% of the time, and will correctly identify a nonuser as testing negative 99% of the time.
Let’s assume a corporation decides to test its employees for opium use, and it is known 0.5% of the employees
use the drug. The probability that, given a positive drug test, an employee is
not
a drug user, is:
(a)
0
.
3322
(b)
0
.
1622
(c)
0
.
6678
(d)
0
.
01
(e)
none of the preceding
Solution to Q2:
Let
D
be the event of being a drug user and
N
indicate being a nonuser. Let
A
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 Spring '09
 ALYAOTHMAN
 Normal Distribution, Standard Deviation, Variance, Probability distribution, Probability theory

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