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Spring 2010
FORM C
Name
Last:_____________________
First:
______________________
Exam 2:
Ch. 4, 5, 6, 7
Section: 64z,
65z,
66z,
67z
(circle)
Directions:
• Put your NAME and CLASS TIME on THIS EXAM and on your SCANTRON.
• Write FORM C on your SCANTRON.
• Each question has exactly one BEST answer.
There are 21 questions.
• You may write on this exam.
There is no scratch paper allowed.
• Each question is worth 5 points for a total of 105 points. This includes 5 bonus points!
• If you have no note page, you must write NO NOTES
on your SCANTRON.
• Put your SCANTRON and PAGE of NOTES inside your EXAM.
When your exam is returned, you
will get back all materials you turned in.
• Turn your cell phone OFF.
Any noise from a cell phone will signal that your exam is over.
FAILURE TO FOLLOW ALL OF THE ABOVE INSTRUCTIONS WILL COST YOU THE 5
BONUS POINTS
___________________________________________________________________________________
Questions 1 – 2 refer to the following:
Last year, 66% of all federal income tax returns were filed electronically. (Source:
http://www.irs.gov/newsroom/article/0,,id=218319,00.html?portlet=7
). Suppose we randomly pick 9 federal
tax returns from last year. We are interested in the number of them that were filed electronically.
1.
The distribution for the random variable is:
A.
P(0.66)
B.
B(9, 0.66)
C.
P(1/9)
D.
B(0.66, 1/9)
2.
Which of the following probabilities is the largest?
A. P(X < 0.66)
B. P(X = 6)
C. P(X ≤ 2)
D. P(X ≥ 7)
3. In the probability distribution function below, X = number of exam attempts to earn a drivers license. Find
the expected longterm average.
A.
1.8
B.
2.1
C.
1
D.
3
X
P(X = x)
1
0.4
2
0.3
3
0.15
4
0.10
5
0.05
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View Full DocumentQuestions 4 – 6 refer to the following:
U.S. college students spend an average of $900 on textbooks each year. Although not given on the web site,
suppose that the data are normally distributed with a population standard deviation of $350.
(Source:
http://www.uspirg.org/highereducation/affordabletextbooks
)
4. Find the third quartile (rounded to nearest dollar) for the amount that U.S. college students spend in a year
on textbooks.
A.
$675
B. $1050
C. $1136
D.
$1552
5.
What is the probability that a randomly selected individual spends at least $450?
A. 0.0993
B. 0.6445
C. 0.9007
D.
1
6.
Consider the two statements:
I.
a randomly chosen individual student spends at most $600 in a year on textbooks or
II.
20 randomly chosen students spend an average of at most $600 in a year on textbooks?
Which of the following is true?
A.
The probability of statement I is greater than the probability of statement II.
B.
The probability of statement II is greater than the probability of statement I.
C.
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 Spring '11
 Liu

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