2010-2 STAT FALL midterm _2 a EC ANSWERS OMITTED

2010-2 STAT FALL midterm _2 a EC ANSWERS OMITTED - Dr....

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Dr. Valerie R. Bencivenga Economics 329 Fall 2010 MIDTERM #1: RIGHT ANSWERS 1. X = price per bushel of cassava ($) 2 3 4 5 .2 .05 .05 .3 Y = price per bushel of wheat ($) 6 .05 .3 .05 .4 7 .05 .05 .2 .3 .3 .4 .3 a.         6 3 . 7 4 . 6 3 . 5 Y E               6 . 3 . 6 7 4 . 6 6 3 . 6 5 Y Var 2 2 2 b. X and Y are dependent, because the covariance is non-zero. c. i y   4 X | y P i X | Y 5 3 / 2 3 . 2 . 6 6 / 1 3 . 05 . 7 6 / 1 3 . . d.         5 . 5 6 / 1 7 6 / 1 6 3 / 2 5 4 X | Y E               5834 . 375 . 0417 . 1667 . 6 / 1 5 . 5 7 6 / 1 5 . 5 6 3 / 2 5 . 5 5 4 X | Y Var 2 2 2
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2 2.a. X = number of defectives X ~ b(x; n, p) where n = 15 and p = .1 E[X] = np = 15(.1)=1.5 b. ) 1 X ( P ) 0 X ( P 1 ) 2 X ( P 4509 . 3432 . 2059 . 1 9 . 1 . C 9 . 1 . C 1 14 1 1 15 0 0 c. Suppose the rule were “return if 4 or mor e bolts out of 15 are defective” 0555 . 1285 . 2669 . 4509 . 9 . 1 . C 9 . 1 . C 4509 . ) 3 X ( P ) 2 X ( P ) 2 X ( P ) 4 X ( P 12 3 3 13 2 2 which is less than 10% (The rule “return if 3 or more bolts out of 15 are defective” results in a probability the shipment will be returned that is larger than 10%) 3. The number of published editorials dealing with education is a hypergeometric random variable , X , because the published editorials either deal with education or not, and they are drawn from a small population without replacement .
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2010-2 STAT FALL midterm _2 a EC ANSWERS OMITTED - Dr....

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