Statistics_2_-_Spring_2002_-_Midterm_1

Statistics_2_-_Spring_2002_-_Midterm_1 - Statistics 2

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Unformatted text preview: Statistics 2 "i'l'flil‘i’i‘ii r. 1 __ First Midterm Exam pi. I. 'n. a] iii-"tn Spring 2002 Printed Name {Please also p flip of each page} Signature _ Student in a: Circie your TA. Iarse Paws! Lasieki Gang Liang James "Jan Cam pen _’ Show your worir. No credit wiii be giuen for correct answers without justification. A correct answer with no justification or incorrect reasoning wiii receive no credit. II"- III : I." I. I I” I a" | llri-Iji 1 - — " _ Problem I. [61 [n the years 1926—199?, the yearly average increase in value of large— -._i J __ company stocks was 13% and the standard deviation was Efl.3%. For long— term L-c- ' ' ' corporate bonds. the average increase was a. l ‘It: with an SD of 3.1%. Both histograms y L I are roughly bell—shaped. is the fraction of years in which large-company stocks lost .3}. “1" moneyr larger, about the sarne as. or smaller than the fraction of years in which long term corporate bonds lost money":I Circle one and explain your answer briefly Same Sin allet ID1- My. '-I:|_.l|-.-. L "Us; 1.1.4 13.". “at I”. rte-1:- wig pig. [M “Lg-.flr’ stink} l 141-7.." -'K . inf:- "11:-l" -._: | - . ' ' -.' ..: . —. -. a'b tw-r' what“ were at 'fi’i'h “l M“ " “‘"t‘" '“3‘ r " "Tn-.1. .I.._.lE lain-t tum-fauna: inter-rttrl'fl-bit- .L-:-“1 'I‘“ r'l“'-"”' ' I _ . I _ _. .U. {ml-II. -'tL-ar LIN-,1 5.12m w r .-'-.1 NIH-1| Jils- 5Trl 3'-i"r'r- '-'“+-" "H “1’1! "-L‘n-r J [3"? .-.J.r1fri~.' |-- iI_IFF'r [1 [unit] " Problem 2. [I5] 5t} observations are taken on two variables and it is found that they have a correlation coefficient equal to .95. True or false and explain briefly: The scatterplot is roughly similar to the one shown below. - c: 13' r GIL-L: '3 .: IJ JUL— '3. . H.321 "‘ _| ‘ L. a he ‘ L r_. t? J 3} " Ll‘1:-~I]hrk Chit" 1"!‘-1‘-'--"t-~ Wfl'r'w at-s' .EI. I'.'IL'."H'. n L luau. » «at r' tn '2- r, a. HUSH-Jill fr" this“. Problem 3 Read the following and then circle True or False and explain briefly. El hours of sleep is termed unneeded Many who get less live longer, study says fihgnkar Vflfiflfltarrt Washington Post Contrary to popular belief, people who sleep sis to seven hours a night live longer, and those who sleep eight hours or more the younger, according to a California study. the largest ever conducted on the subject. The controversial study, which tract-zed the sleeping habits of Li million Americans for six years, undermines the advice of many sleep doctors who have long recommended that people get eight or nine hours of sleep every night. "There's an old idea that people shotild sleep eight hours a night, which has no tnore scientific basis than the gold at the end of the rainbow," said Daniel Kripke, a professor of psychiatry at the University of California at San Diego who led the study, published in today's Archives of General Psychiatry. The study used data from a monumental survey conducted by the American Cancer Society between WEE and 1988. Women sleeping eight, nine and it] hours a night had 13 percent, 21 percent and 41 percent higher risk ofdying, respectively, than those who slept seven hours, the study found. Men sleeping eight, nine and if] hours a night had l2 percent, 1? percent and 34 percent greater risk. of dying within the period. [a'] [T {lid {2] The difference between long1r and short sleepers might be explained by the placebo effect. I "Is-1". I. . __.u I ' I I'- li,'l'_.- Ifills-'1' I -'..b'i-'-|'. 'p'r----- r“: n .I'.-'J.----. 'pi. I __ Ir_._ .I .- *I' I'--' J .- . r- .' :': ___ . .- ii.. ,. [I ,I~r-; .me -~ t..-. -- .- | .- l.‘ .-.r, I. I 1- "' ._l _ I _ I _ . [bl [T5117 '[ [21 A possible confounding tactor is that the participants might not have reported .the amount they slept accurately. .'I:-'- --|'.ir"‘- iii'I-E'IIII'u-‘J:I " I" 1"1b'l.l':"': J'Jl'l: 1' "' u u'..- I -_..«_i.-.I| -._|Ii rii _a~ {is eI -, . lJi"i'---.~ '-.-'.'-1E':I '.3- he .r I‘ -',L-- ,.+_, .r Lf'ir :LH it- -.i -_,I..'_ ,—j,._.' 3 -'|,_',-l__y:l tc} [T 'E {2] This is_.a controlled experiment, but it is not double—blinded "-r- .:1~-'=- mm. - r .J me. .o-r we.- =- -- : I III. I {'- II ILf-I H . I I . . id} [t’fl F HE] A possible confounding factor is that healthier people. sleep more. TEE-.1: 'Li‘l-s-u itril'! ' 5’ - " 3"”: I ' 'fl '." "r' I“: "LIE-.12». .I_!. 'i.- Fwy-Ll '91:: I' I.- '-r,r rite-5r. Ila luff =:-'r'T|'LuLn -it--c win I {warn-“ll: _ . .1 --"- -'-.-!;' -'. ' a:- I "' 'I F'- ‘:'. - l -“‘-r '1' ‘-.-.1'."-|-I°._-'I-I'l'l"-' F:I:KI.I' 4- 'I E'E'I'I'.‘ “It-Ill - 1.,Jl- Ira. 'l'j'lt' fright... {3.93.39} them Problem 4 [6] This year, at surrey was done ef men and wemen who had been divereed and their ages at the time ef the divorce 1were recorded. The results are shewn in the figure belew; the bars for men are light grayr end the bars for wemen are black. Divereed 15 m 311 years :Jlfl 25 In] 34 35 le 49 EU 10 . 5'3 ?t} and Lip True er false and explain: Suppose a yeung wemen is married tdda}r and is tater divereed. She is mere til-ter te be dtvereed between the ages of 35 and 49 than hetWeen the ages of 5D and +59. T-;t'.3;.- -'.r...- an. tap-ts trt+ mt} gut-st “1.4 511' 4:3 2* .3 .~ Stu-T“! the "'"r-i"-£ I ’1'th Lv" ; . In "I" .5. r I . - mt I-t"|.I-".t1J free-fa] '-'I' VHF—“M I: “Dari-5+- L'" 1 '- ' "I FTP-u": Lr". .'—*——-~' I'm I.“ H ' ' . 'n- --q.-. ':r:..t.!’ '~' 5 ,_J [Mb-E 'EKilr'L-PII 4LT KIWI“- Il-nl Art“ .Ilgvfirif.fl_ {$9.1 _- 'r..r.1.lr LJII 2' w-l'q.:]!:{ r.l_1'_-.-|IIJLJ~ .'| t E". '5'"; “5531. f If INK-h Problem 5 [6]. As pan of a quality control program, objects produced in a factory are weighed and those weighing more than 2!] grams. are discarded. Clo the night shift the average weight is. 21 grams with an SD oqord to 1 and on tho day shift the average weight is 21.5 and the SD is I. Eqqu numbers ofitems are produced on holh shins and bod-I. histograms are bell shaped. What perceniage of the discarded items come from the night Shift? -v '_ _ “(learn-Ir ' ‘. 'J'-|| I L111 ME 5 1 L x; _- _ 'u,,.'.:J-I_-|' ft~"~.5m--Ilfl‘i ' “Ll-E") Sill—- ar] .- .. _l a j ' - - _ _ . ..I- I l.— ..7 ‘i 5 “If u. ‘- l r} _ L? I1 I“- _ i‘tt m—rr - w . e- I .I |--_I I II.- J .r'. -. fits-1123. .- | e.) I. u I " H all 55:1“; ELI ‘ _ 1 I L1 __ _| I, | I '- |.'-' I. it“ hlr'i'l H“ “I “warli- J:_F_— . |L' Ir '5' _ ILII iEIfJI'4|.-I:.I'.~‘ I” “J w- w J o-r-r I “am e 3 L; :.v I i. {It It'll-III 1| r_'L-|I_1TJ':-_-. If. Lr ‘I: __ J LJ I HI / 2 If...”. l—FH-l—u' 1— I» 1' r UV} if: r! L I'Jius { I ‘1, -'_l.._/]_:zl.:‘:; -"F.M.[."I:'r:v¢. rL—H L-JI Problem ti. Grades on a midterm and a final have a correlation coefficient equal to .50. The average grade on the midterm is 7'5 and the SD is it}. On the final, the average score is TD and the SE} is 8. The seatterplot is football shaped. A student scores in the "if" percentile on the midterm. tai [4] 1What would you prediet that student’s pereentile snore to he on the Final? -a| "aw than.“ ,1 Ir“: '- ~ ~-r': -!-- II~I|i 'I_' H" I. I II.- ‘lllql Ifi_.._.l_" _' 4 1—1511 '_ I 'I -. I. I _| — 1 :I I H: “H. —'I-r . . ___ a, «3;: at; .r 9.24 .1 -|n'=: Iain" t 2'.“ at, e). —tt-u~ Haj“ anal-atria I I Eh] [4] Approximately, what is the chance the student 1will be above the 9ft” percentile on the final‘.i " '_F . -. .""«. 'II-"' ""i' e r"-'.'—- .... 1J‘r_.__IIJ_-rf_.—I_.._ , i._.!:l'| 1:. i I_._- in}. h: 't 't "t 1 tr- r. [LLL IE2“. H a. Table {pun-mt! .10. NOW TABLE I H 910911! Arm ——1—.___ 0.00 09.00 {:1 0.05 39.04 5.00 0.10 59.59 1.91 0.15 30.45 1 1.02 0.20 30.10 15.55 0.95 0.30 0.35 0.40 0.45 30.1571r 30.” 31.52 35.03 315.05 35.21 30.29 30.29 41.31 55.52 45.15 52.50 45.45 51.55 51.51 30.“ 54.51 20.97 50.53 21.00 150.49 20.51 53.19 25.41 55.99 I914 13.50 23.37 3|.00 34.13 0.50 0.55 0.00 0.55 0.10 0.95 0.00 0.05 0.90 0.95 1.00 24.20 55.21 1.05 52.99 10.55 1.10 21.19 12.51 1.15 20.59 14.99 1.20 19.42 15.99 10.25 90.01 11.14 00.64 15.04 02.30 14.97 03.05 13.941 05.29 1.15 1.30 1.35 1.410 1.45 1 15013111 Am: 'H—‘—'—I—5 1.50 12.05 015.54 1.55 12.00 01.09 1.00 11.00 00.04 1.155 10.25 00.11 1.20 0.4-0 91.09 1.15 0.05 01.00 1.00 1.00 02.01 1.05 1.21 05.51 1.00 15.50 04.215 1.05 5.015 04.00 2.00 5.410 05.45 2.05 4.00 05,015 2.10 4.40 00.45 2.15 5.00 95,511 2.20 2.55 01.22 2.25 5.11 511,515. 2.30 2.03 01.015 2.35 2.52 00.12 2.40 2.24 00.515 2.45 1.00 00.5? 2.50 1.95 90.915 2.55 1.54 00.02 1150 1.35 00.01 2.05 1.10 00.20 2.00 1.04 99.3: 2.25 0.01 00.40 2.00 0.10 99.49 1-05 0.159 99.515 2.00 0.150 09,151 2.95 0.51 99.55 ' 3.30 0.172 H0110: {Pt-1:011:11 1 1"“!£1501 .1011: m 5.05 0.551 99.111 5.10 0.521 99.505 5.15 0.219 99.551 5.20 0.555 99.353 3.3 0.103 99.005 99.903 99.910 99.933 99.9411 3.35 0.1445 3.4-0 0.|23 3.415 0.104 3.50 0.00? 3.55 0.013 3.50 0.015] 3.05 0.05I 3.10 0.041 99.953 99.90I 99.950 99.914 99.9'1‘0 5.15 0.055 99.955 5.50 0.029 99.955 5.55 0.054 99.955 5.90 0.020 99.990 5.95 0.015 91.951 4.00 0.015 00.0051r 4.05 0.011 00.0040 4.10 0.000 00.0950 4.15 0.001 99,915.57 4.20 0.0515 99.9913 4.3 0.005 99.9919 4.50 0.1104 99.9955 4.55 0.005 99.9955 4.40 0.052 99.9959 4.45 15.002 99.9991 ...
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This note was uploaded on 10/31/2009 for the course STAT 131A taught by Professor Isber during the Spring '08 term at University of California, Berkeley.

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Statistics_2_-_Spring_2002_-_Midterm_1 - Statistics 2

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