This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: ECON 506M Quiz2B, October 4, 2007 NAME: I. Let Y be a random variable distributed as following: Y P(Y) 1 a 2 b Assuming E (Y) = 1.5, find the values of a and b. (8 points) Here you have to solve a system of equations (2 equations and 2 unknowns, a and b). 5 . 5 . 5 . 1 2 1 5 . 1 ) ( 2 1 1 = = = + = = + = + a b b b Y E b a b a For the rest of this question, assume a = 0.3 and b = 0.7. Find the variance .( 8 points) For the variance we need to get the first and second moments. 21 . 7 . 1 1 . 3 ) ( 1 . 3 2 * 7 . 1 * 3 . ) ( 7 . 1 2 * 7 . 1 * 3 . ) ( 2 2 2 2 = = = + = = + = Y V Y E Y E Find E( Y 5 ) (6 points) 25 . 3 ) 2 / 5 ( * 7 . 5 * 3 . ) / 3 ( = + = Y E II. A politician believes that 40% of voters would strongly support a proposal he wishes to advance. Suppose that this belief is correct. 5 voters are approached at random. What is the probability that at least one of the five would strongly support the proposal? (6 points) In this case we need to use a binomial distribution, since n=5 is fixed. Suppose that we consider a success when a macroeconomist support the proposal (then p=prob of...
View
Full
Document
This note was uploaded on 04/14/2011 for the course ECON 506 taught by Professor Staff during the Fall '08 term at University of Illinois, Urbana Champaign.
 Fall '08
 Staff

Click to edit the document details