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Economics 70 Book Exercise 1
Exercise Title: Homework 1
Date: 5/7/2009
Name (Last, First): ANSWER KEY
PID:
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1.3
a. The population consists of measurements on variable of interest (top speed,
range before recharging, time to accelerate from 0 to 60) for all
Tropicas
that
have been manufactured to date, or that will be manufactured in the future.
b. The figures given were based on the sample.
1.5
a. The population of interest consists of a series of measurements (damaged or not
damaged) taken for each pine tree in Yosemite National Park at a particular point
in time (either 1985 or 1990).
b. The percentage are probably estimated.
c. One possible method is to divide the park into a number of grids and to sample
trees randomly within each grid. If the trees are numbered by the park rangers
using some method of categorization, this numbering system might be employed.
2.10
a)
Fraction
Debt Per Capita
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0
.1
.2
.3
.4
.5
b)
1
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Taxes Per Capita
700
1000
1300
1600
1900
2200
2500
2800
0
.1
.2
.3
c) They are similar – they are both skewed to the right.
2.29
a)
Average per capita debt = 92124/50 = 1842.48
b) The median is the average pf the 25
th
and 26
th
ordered measurements or
(1225 + 1300)/2 = 1262.5
c)
The mean is much larger than the median.
Hence, there must be some unusually large
measurements that inflating the value of the mean, and we conclude that the distribution
is skewed to the right.
2.38
a)
First calculate the intervals:
04
.
16
80
.
15
)
04
(.
3
92
.
15
3
00
.
16
84
.
15
)
04
(.
2
92
.
15
2
96
.
15
88
.
15
04
.
92
.
15
to
or
s
x
to
or
s
x
to
or
s
x
±
⇒
±
±
⇒
±
±
⇒
±
Using Tchebysheff’s Theorem, we would expect at least (1 – 1/1
2
) = 0 of the
measurements to fall in the interval 15.88 to 15.96; at least (1 – 1/2
2
) = ¾ of the
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This note was uploaded on 04/14/2008 for the course ECON 400 taught by Professor Turchi during the Spring '08 term at UNC.
 Spring '08
 turchi
 Economics

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