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Mid1_KeyA_E41_F08

Mid1_KeyA_E41_F08 - Economics 41 UCLA Fall 2008 NAME(Print...

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Unformatted text preview: Economics 41 UCLA Fall 2008 NAME (Print) by A October 20, 2008 Midterm Exam I. TA Name & section time: - The normal table and some formulas are On the last page ofthis exam — Only pens, pencils. and crasers may be used — this is a closed book, closed note, exam. — Students may use an ordinary calculator, but nothing that can access the internet. - This exam consists of 15 True/False ? (30 points) and 10 short answer ? (30 points) and 4 problems (40 points). - Clearly write answers on this exam. No points are awarded for illegible answers. - Be prepared to show a photo ID during the exam (e.g., UCLA ID, driver’s license, or something similar). - You may leave when finished. Turn in both the exarn and your scantron. Do not disrupt those still taking the exam. I. Circle either T for True or F for False (2 points each, 30 total). IQr F A sample correlation coefficient may be calculated between two quantitative variables, but NOT two qua itative (= categorical) variables. 2) T or®Time series data on one variable can NOT be represented in a histogram. 3) T [email protected] If the sample correlation coefficient between X and Y = 1, then the slope of an estimated regression line of Y on for the same data sets must also = 1. 4)®)I’ F The U.S. national “federal" government budget deficit is a flow variable. [ i . IQ t? 5) T or®For all boxplots‘ the “whiskers" extend to the furthest observations which are less than 1.5 quafliles below the first quartile, or 1.5 (3.96“? above the third quartile. 0:3 66)“ F For a histogram with relative frequency on vertical axis, one can not determine the number of observations 7) T or®The slope estimate for an ordinary least squares regression is “resistant" to outliers, but not the sample correlation coefficient MW 8) T or®0iily data from a population that is normally distributed can be “standardized. ” 9) T or®For any “reverse regression” the estimated slope: b" is the reciprocal of the estimated slope of the forward regression: b1 l x—ll , . . . . 1 ‘" a . . 10) T or®Since the formula for the probability of a normal distribution = ———e 2[ ] the normal probability JVZK density curve is highCSt when (x—tt) is largest. 11) T or® For three observations: 3, 4, and S, the sample standard deviation = .8165 . . . . ’3}. 12) r F 5. IS a statistic, while ‘. is a parameter. 13)®or F An observation may be an outlier in univarate analysis, but not bivariate. 14) T or An outlier must be an influential observation. 15) T or®lf the sample correlation coefficient = 1, then we can be confident that changes in X cause changes in Y. yell/i Omani 69W? raunrlmg of 2 - Mid I . BRIEFLY, clearly and correctly ansvver the following ten questions (3 points each, 30 total). 1) The time required for individuals to complete an exam is normally distributed with mean = 56 minutes and a standard deviation of4 minutes. If students are 'v ish, find the proportion who will complete the exam. V l 2. 2) The scores on a university examination are normally distributed with a mean of 50 and a standard deviation of 10. If the tap 16 % ofsrudents earn A's, what is the lowest mark that a student can have and still earn an A? .Btn. = “-7? a" 936% : “To” x: 50+ 5: 39¢ -- I ' 5“:- .399 e. X: ro'l 9‘1”; '67 _F _._ Ci- ‘ " etfllhflr- 0k .. _——~-*’ 3 3) An economics department with 40 all-male faculty which hires two per year, has two retirements per vear (each after a 20-year career) wants/tedravéZS‘W female faculty. What will. be the gender of the flow ofnew hires ifthis goal Is to be metinIOyears? IF‘EMIE’ .l lmlP Per VW. so. a: remit P’DW m_hw_ _J__ ..___._.._ _ _ .,.._ ‘ .. 3 4) For an ordinary leaxscluares regres ' ' e, if x = X , what is the predicted height of the regression line for this x? Y )(r )L 3 S) The average earnings of individuals with an undergraduate degree in economics is higher than for individuals with an undergraduate degree in business administration. Briefly give three reasons provided in class. —€ron peel}! psi real wade“) _ {From pnptlot underage?! m‘[email protected] 8H9 itself/ism lush FlanrLtl“ fl HOV luajiré go in g‘ml retrial“) 6) Use the regression output below. The dependent variable, W = hourly wage. The independent variable, LOS = length of service (in months). What is the predicted wage of a worker with 10 mo of “service" (experience)? Regression Statistics H we (8+ Adrian) LOS 0.40 Nev/4 7) The diagram below show the number ofjumps for each of 24 student. The variable we consider is number of w!“ jumps. at x L6ltklflll9 x x l x x x ‘ x x x x x x x \ x x x x x‘ x x x x/ l m t try n fit": '41 en Etc: =0:‘: I Number 0! Successfullsumps What IS the median ;a.nd the mode: [Jr-ta] ll a W 8) In the f ula from the text and class: ——e ,what is the numerical value, 0 (three significant digits)? 0J5:— 9) What jsminimized in fitting an ordinary least squares regression line? Use summation notation, not words. \(Eeaz W {(77% Dr EGWbD—hMB—L 0W2; 10) A sample 0.4-0rkers are classified race A bar graph of the results is given below, but the bar for blacks in the graph below has been omitted. What IS the propor______t___r'on of black workers 1n the sample? II ., ‘2 6’3 (5’0 COURT I] I! white black asian other HI. Clearly, concisely, and completely answer the following problems. Show your work. (10 points each, 40 total). a f f 1) Let X hourly wage feta sample of 9 workers. The values of X are: 30 34 55 15, 20 18.2S,18 2_8_ a) Make a stemplot to the tar right (do not “Split stems ) and a histogram with classes: .x ' “"x\ . below, as- done in Ihfijfilxt (with lower but not upper values included) x Era. _"" .200 ’9 Pa .3, If! m--__.,--..- b) What is the (sample) Mean? 0) What is the First Quanile, Q.? (use text‘s method to find Q. and d) What is the Interquartile Range (IQ KoxlA I 2) Consider the following data on X and Y: 21)- Find val *‘u' i) D: 1-] ii) it»)? i=1 iii) (in)2 72“ W ——-—~ ,=. 5 (u. LIM- 2c “(56‘ nfl (1027) b) Use either your calculator or the rmulas on the last page to find: - l 5‘ 2 b1 i. t i '3 A - I‘ g 6 i) sample correlation coefficient - 5 li a 1 ii) slope of the animated OLS regression Ii with x the independent variable iii) intercept of the estimated OLS regression line with x the independ 1 variabl’: '5 b to -. \t lax '~ ii- — .. =2 75+ 17011: ll‘l'; w bm-uw..." W 3i Consrder Excel output to the right. W Regression Statistics Y = overseas returns (in %) and X = US. returns (in 9:3). 31:13:? 33338 _ _ g . X = 3 and Y-= S s = 4 and sY = 6 Coefficients V:- '2 '5 -l-. q x Intercept 2.30 a) For the forward regression Y = b +b X what is the predicted US 0.90 value for overseas returns if 3 _ '5 hit = 6 12’ q . '" 1 - .. 9 - ‘ i ’2 7- ' ’ ._ U_S. returns are. 5 percent. U-S. returns are 11 DEW-W i ' l5?) - '3 “,IICSS mouse A _ _ _ ': i - what Is the pred1cted value for US. ret ‘ -. - [flier-I} he .W regression X = 1 Overseas lrenrtmsB are: -5 percent. Overseas returns are 11 percent ”3‘3 ’2' ”.4613 or a particular population, assume test scores 0 ow a no 1 I1 11 ton w1 popu atlon mean = , an population standard deviation = 80 '20 D a) The standardized z—score corresponding to a. raw score X = 800 = 325 7' ,1 b) What proportion of this population sowed below 800? qq 3 2 '1. a so too A, c) What proportion of this p0pulation scored between 650 and 800 .2 9 U c . i 2 g A: . E 3 .‘mav .73” =,2€8| ' d) What test score would a student need to have a higher score than 90° .' o Iuiation? 18 r. ‘KebOU “-4 : I. ,8” x 601mm: 2. e) What test score would a student need to have a higher score than 80° 6 population? N L ‘ X'690 \{3 004-67.} thj-r E 6 1’ ...
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