Economics 120A
Name:
________answer________________
Professor Yongil Jeon
Summer 2007
Student ID#: _________________________
Answer to Homework #2 – Summer 2007
(Final Exam, Summer 2006)
Answer all questions on separate paper. This problem set should be handed in to TA Deniz
Kebabci at the beginning of your review session on Tuesday, July 31, 2007.
Problem sets may
not be handed in once solutions have been distributed.
Please write down your name and PID
clearly. Good luck!
1a)
(3 points)
The standard normal probability table
A)
is equivalent to a t distribution if the sample size is less than 30.
B)
shows a normal distribution with standard deviation equal to zero.
C)
is used to make inference for all normally distributed random variables.
D)
None of the above.
Answer: C
1b)
(3 points)
The sampling distribution of the sample mean, when sampling from a normal
population with mean
µ
and variance
σ
2
is:
A)
normally distributed with mean
µ
and variance
σ
2
.
B)
normally distributed with mean
µ
and variance s
2
.
C)
normally distributed with mean
µ
and variance
σ
2
/n.
D)
normally distributed with mean 0 and variance 1.
Answer: C
1c)
(3 points)
Suppose that you mistakenly move the decimal point to the right one digit in
data from a normal population with a mean of zero.
What happens to the standard
deviation?
A)
Data with mistake has standard error ten times the original.
B)
Data with mistake has same standard error as the original.
C)
Data with the mistake has twice the standard error of the original.
D)
Data with the mistake has one hundred times the standard error of the original.
Answer: A
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Answer to HW #2, ECON 120A, Summer 2007
1d)
(3 points)
Which probability distribution is appropriate for testing hypotheses
concerning an unknown population mean when the sample variance is used to estimate
the population variance?
A)
The normal distribution with mean
µ
and variance
σ
2
.
B)
The normal distribution with mean 0 and variance 1.
C)
The standard normal distribution.
D)
The t distribution with n1 degrees of freedom.
Answer: D
1e)
(3 points)
Which of the following is not
true regarding the Central Limit Theorem?
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 Summer '08
 Jeyeon
 Economics, Normal Distribution, Standard Deviation

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