2007 Exam4.2 Solutions

2007 Exam4.2 Solutions - IE 111 10:00 Section Exam 4 Fall...

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IE 111 NAME __________________________ 10:00 Section Exam 4 Fall 2007 Instructions Open book, open notes Clearly indicate your answer You must show all relevant work and justify your answers appropriately Partial credit will be given, but not without sufficient support Each question is worth 33.3 points You do not need to interpolate in tables. Just pick closest value. 40's 2 Mean 76.2 50's 6 StDev 13 60's 0345778 N 29 70's 0155779 Med 77 80's 000126799 90's 2469 100's

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Consider the following joint distribution of X and Y: X 0 1 Y 0 0 0.6 1 0.4 0 a) Find the marginal distributions of X and Y f(x) f(y) P(X=0) = 0.4 P(Y=0) = 0.6 P(X=1) = 0.6 P(Y=1) = 0.4 b) Find E(X) and E(Y) E(X) = 0*0.4+1*0.6 = 0.6 E(Y) = 0.4 c) Find V(X) and V(Y) E(X 2 ) = 0.6 V(X) = 0.6-(0.6) 2 = 0.24 E(Y 2 ) = 0.4 V(Y) = 0.4-(0.4) 2 = 0.24 d) Find COV(X,Y) COV(X,Y) = (1-0.6)(0-0.4)(0.6) + (0-0.6)(1-0.4)(0.4) = -0.24 e) Find the correlation ρ xy 1 ) 24 . 0 )( 24 . 0 ( 24 . 0 -
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This homework help was uploaded on 02/26/2008 for the course IE 111 taught by Professor Storer during the Spring '07 term at Lehigh University .

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2007 Exam4.2 Solutions - IE 111 10:00 Section Exam 4 Fall...

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