stat130 f00 quiz1 Rein

stat130 f00 quiz1 Rein - Quiz 01 Statistics 130 Fall 2000...

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Unformatted text preview: Quiz 01.doc Statistics 130, Fall 2000 _ Answer questions briefly in the space provided. Thinking carefully before writing pays oft".f study comparing the length of colds for those who take Echinacea and those who don‘t. Each particip - was asked to keep track of the length (in days) of each cold they had October through March. Of the 599 ' people who did not take Echinacea the average length of colds was 1.8 days. Of the 215 people who voluntarily took Echinacea to prevent colds the average length of colds was only 1.5. This difi'erence is large enough that it could not have occurred by chance alone. 1. Are there any extraneous differences (or confounding factors) that may make this study difficult to evaluate? Give one or two examples of such possible differences. - ._..I v _ _ ' , ,,, ‘ . - 7 a"? I’fifiszrr‘JRW‘W-“yfl -.‘—'-5" r "" are" —1e'r- I... D:— 6 ’ -_..l-_;_—.—-Ila-I-,':’l ‘ -.._.—- ._ f-‘P’aw —- 3-4". 4 ’k“ J -A,.v.-a=;—arq::-'l¢.ll.lg;e_-=.—— r 5‘Pr'r pill-1'4" '1‘," "la ,evrf'l-gw-v-v Some forums «Hm? cum/ct mat/2t ‘ W .4 Mam/7’2 MMM 54776th Wop/c Mm 4mm amt/mam Md Ace/nadir IMMM ‘E We i/l/I/l ‘f/f/ia/Uf Wq/twmrmzmt/s "‘ M75 flaw (7’ 0mm?- MCUJam/ c fflbrrmrwt “WW7” Madc’mc (me! 914%“. \ 171.2 €XP/EW W Mae/fig! Qfi‘, 0M6)” W «We mp ar 0 no??? Mad Ufidi‘fi/{ufiww 2. Can we conclude from this study that taking Echinace ortens colds? Why or y not?‘ no we can not dmafiqate {mu «ta/km W/flflflflt .9th Oar/ole War on m KLWBQ/ beam/0m w an WMWCHW Wot?) WW WI MWLW/D’. find m MHz/n 0w, W6 (amour (we/W, flora/W 0,” M dam W 0._MMM,W m MW Moms mWC/- 3. If the Echinacea treatment costs about $45 per person for the length of the cold and flu season would you think it worthwhile, even if effective? Why or why not? «rye-amt It Wat 196 WWW beam it is Wm “that 06th WM?) m ' {HI/l m0+ dama?c it, as Liam M ebb/W): J dm'i Mini/11+: mun/h WLMVM 0Q , Ma 4 ' :84 ‘ am Mama 3 W i2? do w 16 an Worth ‘ . (7 Wii‘f'fla v Quiz 02.doc Statistics 130, Fall 2000 Rein Answer questions briefly in the space provided. Thinking carefully before writing pays off! 1. Airlines compute the percentage of flights that are on time to be the percentage that arrive no later than 15 minutes after their scheduled arrival time. a. Is ' a valid measure of on-time perfonnance? Explain. 09mm M a yaw/at 03 on} / l "Fm/w memmmae Mamie, 4746 747er W Mam-m 7 mm W [m flat 5% W , WW. / pet‘s [Ml/LU rs Mme/m Maya/coat WWJxm WW/f- b. Isthisareliable measure? Explain. ‘ I I ’W’WWM a WW6 mam a! /s““ nut/tea; 7%: W _ 06m be M/a/ng/WW‘ fl£§¢ fifl/Z We 4% mfi/m/flm‘ mflm girls saga/mam 45m. 2. If we conduct a study to determine the relationship (if any) etw city of orig: , scheduled departure time and whether the flight is arr-time or not, identify each variable as explanatory or response. 61+? 0? m h 'zxpfmayhmj, . Mama own/marinate “ exp/mainly” Mahme fl/l/lm‘W 3. Identify the method of sampling if we sample flights fior this study so that each of the 8 major airlines (United, American, Delta, USAif, Southwest, Continental, Northwest and Alaska) has exactly 200 flights in the dataset. [Lt/4ain Jim/2de @MW/qdé. 1 / ' n K“ t r. _/| Quiz 03.doc Statistics 130, F all 2000 Rein Answer the following True/False questions for one point each. 1. E 'fie’standard deviation of a dataset is always smaller than the mean. True . 2. m A dataset with a skew-left histogram has a mean that is smaller than the median. fill-V101 l’: WiOl/C _ , 6.0mm! mph 3. T HA 5 A dataset with a symmetrical histogram has about half the data values above the mean and about half below the mean. 4. ELM Eutliers influence the mean. 5.T% FOutliers influence the median. 6. iOutliers influence the quartiles. 7. Fa lSC If the standard deviation of a dataset is 0, we can conclude that all the values in the dataset are zeroes ' ~ 7 (F W IS $6 5 0 4m came a: 8. ' I E M CAbout 2/3 of the area in a normal distribution is in the mean plus or minus one standard deviation range. NE: (www.mi (if; 2M ,-~ "" 4+ . v 9:7 mm W 7590 . . 9. T r If we know that salarie bf wbrkers 1n the state of Callforma have mean level $40,000 and standard deviation $25,000, we can conclude that about 2/3 of California workers v sal ' in 11% $15,000 to $6 00 r ge. . W W mwafiw N v~ ’lO '6 H0 (96 010 10.. W C If we believe that the birthweights of full-term infants follows a normal distribution with mean 8 pounds and standard deviation 1.5 pounds, we can conclude that / 1 Quiz 06.doc Statistics 130, Fall 2000 Indicate whether the following four statements are True or False for two points each. I. If two events are independent, that means that they cannot simultaneously occur. m9?” " A Mr: OPP/Mbflb’lllg 13 that \l‘ L .W anM+: PM ml warm; t? W WM MWVK,W C-A/mmfimwmem 0cm. M If the chance that I roll a six on a die is not in rolling a six on the first roll is independent 0 true 2. fluenced by whether the previous roll was a six, we can say that f rolling a six on the second. 3. If there are only two possible outcomes to an experiment, because the sum of the probabilities must be 100%. Was/Wu: 0th +0 {00% , 171% the chance that each one occurs is exactly 50% mam deter/2% WM) mm hash lace 9070‘ 170K exam/(ems (me could have a 70% mama ugh Mal mm: (mm have A 519% aha/me. Eighty percent of Cal Poly students were in the top 25% students are no more or no less likely to he in the top 2 Poly students. Using this information, answer the fol] of their High School graduating class and male Cal Poly 5% of their High School graduating class than female Cal owing questions for 2 points each. 4. What is the chance that a randomly chosen Cal Poly student is a female who graduated in the top 25% of her High School class? +0 sot WW3 = 263% aft eta-Em WW’CZ:59"’v Eb: Pl malt) — 60/. “Female-é m hwy/a?) = WPer 5): P(A)r?(s) 1-.4000—7 5. What is the chance that the student I select 15 a male who dld not graduate in the top 25% ofhls High School class? I * Plno’rAVPM) PLmMa)‘ .50 W‘th‘rfiavlo Fitnch 2' mafia: (.90)(.se) 2.1000 -7 my, School classes? P(§W0Lm+51n’lwa§%)=(.%0)3 : .6121) : 51% l 9: rim/that mm m act/we hash add «HWY 4% 3mm M0133. : LlO°/o mm Quiz 07.doc Statistics 130, Fall % close sample proportions are to the population proportion. What is an equation that would allow me to calculate this standard deviation? 6 .0, r p( l e ) Fl 2. Suppose you take a simple random sample of Cal Poly students and ask each his GPA. Suppose also that the mean GPA of students is 2.89 and that the standard deviation of student GPAs is 058. Is it likely that the mean of 100 randomly chosen GPAs would be 3.00 or higher? Explain. X12955? so»: 058- \ HUI/HMS Medal not he “Wilt/f too'AZaUJ D€CtUAA£-lnlhttjtult OPgflinuowx Pl )3 Z 3. go?) imam H" fifth/S that as mam tVlUFKHSES (Xfi,/flqg pdpnalajiahJ dLMVaMA. 3. Suppose you take a simple random sample of Cal Poly students ask each his age. Suppose also that the mean age of students is 21.3 and that the standard deviation of s is 1.68. prossible, determine a range of i 1 age values would contain about 95% of the sample means we could see for samples of size 100. Ifnot possible, ’ (a g 1 ' h . . . a ‘ / 6::IHWYTI \ J/ a: :llfll ‘ (2— ': ---——'-" ""—' a r _ - . , ./ X I o , m—mm- « 5 3 . ' ' mags: 8’0.de ~Jl.b3& ‘ 8mwkyyflm New . ¢%fim *- ‘. 3 30 wfiwi 20% 3th 21. {05b 4. If, in fact, 9% of Cal Poly students are vegetan' and we are to sample 250 Poly students at random, what are the expected value and the standard deviation of the percentage of vegetarians in the sample? 11/02/00 ...
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stat130 f00 quiz1 Rein - Quiz 01 Statistics 130 Fall 2000...

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