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Statistics 13A, Spring 2010, Practice Midterm III Version A
Name:
ID:
Instructions:
•
50 minutes, closed book midterm
•
one lettersized (doublesided) “cheatsheet”, hand
held calculator and scrap paper are allowed
•
20 multiple choice problems, 5 points each
•
•
hand in
both
this midterm and scantron (the midterm
will be used as a proof of your presence in the un
likely event of missing scantron)
•
grading is based on scantron which will
not
be re
turned to you
•
this is Version A,
please mark the corresponding
circle on the scantran
•
In the actual exam, the necessary tables will be
attached. In this practice exam, please refer to
the tables provided by the textbook.
•
good luck!
Midterm begins here.
..
1. Which of the following statements is true with re
gards to continuous random variables?
(a) The height of the probability density curve
shows the probability of an event
(b) Probability of any event is strictly positive
(c) Probabilities of events are determined from ar
eas under the curve
(d) The probability distribution is always bell
shaped
answer: c
2. Let
X
be a continuous random variable and
c
be a
constant. Which of the following statements is
false
?
(a) The probability that
X
assumes a value in the
interval (
x
1
,
x
2
) (where
x
1
<
x
2
) is the area un
der the probability density function between
x
1
and
x
2
(b)
P
(
X
=
c
) =
0
(c)
P
(
X
≤
c
) =
P
(
X
<
c
)
(d)
P
(
X
>
c
) =
1

P
(
X
<
c
)
(e) None of the above
answer: e
3. Suppose
Z
is the standard normal random variable,
what is
P
(
Z
>
1
.
35
)
? (choose the closest answer)
(a) 0.9115
(b) 0.0885
(c) 0.67
(d) 0.67
answer: b
4. The
z
score representing the ﬁrst quartile of the stan
dard normal distribution is approximately (choose
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 Spring '10
 samaniego
 Statistics

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