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14.30 Introduction to Statistical Methods in Economics
Spring 2009
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#2
14.30

Intro. to Statistical Methods in Economics
Instructor: Konrad Menzel
Due: Tuesday, February 24, 2009
Question
1
Recall that a random variable
X has the binomial distribution if
where n is the number of trials and
p is the chance of success. For the following
crudelydisguised questions about the binomial distribution, do the following: Define
p, n, what the specific "trials" are, what "success" is. Then write down the relevant
distribution and answer the specific question.
1. If 25 percent of the balls in a certain box are red, and if 15 balls are selected
from the box at random, with replacement, what is the probability that more
than four red balls will be obtained?
2.
(3 pts.) Suppose an economist is organizing a survey of American minimum
wage workers, and is interested in understanding how many workers that earn
the minimum wage are teenagers.' Suppose further that one out of every four
minimum wage workers is a teenager.
If the economist finds 80 minimum
wage workers for his survey, what's the probability that he interviews exactly
14 teenagers? 35 teenagers? What's the probability that he gets at least 5
teenagers in his survey?
3. (Bonus Question) A city has 5000 children, including 800 who have not been
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This note was uploaded on 01/30/2010 for the course STAT 430 taught by Professor Jones during the Fall '10 term at Napa Valley College.
 Fall '10
 jones

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