(6 pages; revised 06/24/08)
Page
1
of 2201 Quiz 02
Louisiana State University
EXST 2201
Quiz 02
Summer 2008
Name: _________________________
Section: __________ Score: __________
Due:
July 2 and 3, 2008
(100 pts)
Directions
:
Put your answer (letter) in the associated blank. You may use any book and talk to any person.
You do not have to show your work to get credit.
1. Suppose a random sample of size 34 is obtained from a population with population mean
30 and population standard deviation 4.
A. What is the shape of the sampling distribution
of the sample average? ………………………………………………….
_____ (5 pts)
a) Unknown shape
b) Bell shaped
c) Block shaped
d) Horn shaped
B. What is the mean of the sampling distribution
of the sample average? ………………………………………………….
_____ (5 pts)
a) 0.88
b) 8.50
c) 30
d) 120
C. What is the standard error of the sampling distribution
of the sample average? ………………………………………………….
_____ (5 pts)
a) 0.118
b) 1.133
c) 0.686
d) 0.882
D. What is the probability the sample average is greater than 30.2 ? ………
_____ (5 pts)
a) 0.2514
b) 0.3859
c) 0.7486
d) 0.6147
E. What is the probability the sample average
is less than or equal to 30.6 ? …………………………………………… _____ (5 pts)
a) 0.1909
b) 0.6423
c) 0.5768
d) 0.8078
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Page
2
of 2201 Quiz 02
2. A simple random sample of size
n
is drawn from a population with.
xbar
=
59.2
sigma
=
3.8
A. What is the point estimate of the population mean?
_____ (5 pts)
a) 3.8
b) 55.4
c) 59.2
d) 15.6
B. What is the 90% CI estimate of the mean if
n
is 45 ?
_____ (5 pts)
a) (58.3, 60.1)
b) (59.1, 59.3)
c) (58.1, 60.3)
d) (58.3, 60.4)
C. What is the 90% CI estimate of the mean if
n
is 55 ?
_____ (5 pts)
a) (58.4, 60.4)
b) (58.2, 60.2)
c) (58.4, 60.0)
d) (59.1, 59.3)
D. Increasing
n
causes the confidence interval to become?
_____ (5 pts)
a) No change.
b) Wider.
c) Narrower.
d) Taller.
3. A simple random sample of size
n
is drawn from a population with.
xbar
=
35.1
s
=
8.7
A. For a 95% confidence interval and a sample size 20, what is the
critical value?
_____ (5 pts)
a) 1.645
b) 1.725
c) 1.96
d) 2.093
B. What is the 90% CI estimate of the mean if
n
is 40 ?
_____ (5 pts)
a) (32.4, 37.8)
b) (32.8, 37.4)
c) (32.4, 37.4)
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 Summer '08
 McKenna
 Normal Distribution, ........., Statistical hypothesis testing

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