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Test2Key - MATH 220 7 TEST#2 NAME D0 WM" 1" 5...

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Unformatted text preview: MATH 220 7 TEST #2 NAME D0 WM?" 1": 5 SECTION c» SHOW YOUR WORK! HONOR PLEDGE: I have neither given nor received help from any person on this exam. Signed l. Bigger animals tend to carry their young longer before birth. The length of horse pregnancies from conception to birth varies according to a roughly normal distribution with mean 336 days and standard deviation 3 days. What proportion of horse pregnancies last between 330 and 340 days? ‘ g {‘3 7 * " ‘ r “' ' $7 4 lv 3 e i. s "< = X: fwi‘: 01‘ lam/2a Warm}! WW“ M 5W} Fifi 3a] $3“ 9'00; F J “fl'k um 1:: .s,‘5<.. X (ppm. hernia .. i < 532931]; (3.6mm (roam e 2 3 g g i fl: 4% (£44,5- '” f ‘ {L‘Efibf wimp i'P‘dOan'éVfl/l 2. Final averages are typically approximately normally distributed with a mean of7f and a standard deviation of 12.5. Your professor says that the top 8% of the class will receive an A. What average must you exceed to obtain an A? X 1 {girl WW \l 4 1w I”? H9?;‘,}&€ (H \‘L 6% 19:5 \ ' ' I“ 1 73\ £3 y *3? : 1- 1“ (“1'59" +7‘1 5 1 WIS .‘WMWWW WM J“ V - 7; y ~ g‘lrb 3. In California, 30% of the people have a certain blood type. What is the probability that exactly 3 out of a randomly select group of 7 Californians will have that blood type? V‘.‘ " {aii’irxrxfazxa ham Ethel "WW, 4 X: “erythf’y' in X birtmwrfi‘, a: ,1"; +1 2 y; t; 7’ IL; i I p r. ‘S , a"; gawk: [Li’xlfgymfisf‘i I 7 9”“, a} (.53 {ha ct Sit/'7'3li': ‘ 4. Four of the 20 students (20%) in a class are fraternity or sorority members. Five students are picked at random. Does X = the number of students in the sample who are fraternity or sorority members have the binomial distribution with n = 5 and p = 0.20? Explain why or why not. , .4 ~ r .. -’ 4 7L! :— 4} dial-wt dl” 5 fflfigifif I"- s 1 “A C“ ‘ :3 1 {mt C“, “5513f ;; files‘tltcfg f , I . .3 1: 1 Pei Wait a"; atria; Wfflltle‘t 5. Suppose that 40% of adults are committed to eating nutritious food when eating away from home. You operate a restaurant. To help plan your menu, you decide to conduct a sample survey in your area. You will use random digit dialing to contact a simple random sample of 200 households by telephone. a. What is the mean number of nutritious conscious people in your sample? ‘ v . - . I r .’ ‘ _, i X“ i? of e’dmfij M 3' A 6-043 wnc 5m? (MW? “’rl in" 6777427 91545“. ><_ .b~’l\; L's»; ‘13: area; .tf— riff; {Matti *i i6 » h :1 1003"" b. What is the probability that at least 95 people in your sample seek to eat at trifle-dc H food when eating away? ‘ - ‘ ‘r '7‘; :f‘ i gmug j; -r m;- .: if“ J-“f;‘_,' {,1 ‘- tL , , 2" .a “it w {{f?§_§f, a as; v. I; a 9;?) F E‘ Z x A at ii 55‘} b I I J a 7; I’r-y ( >w ’ a) E — ‘~ i w; . , \\ 6. Name the type of sample survey bias existing in the following: (p I ,1 fix}? ; $.32. a a. “More than half of Califomia’s doctors say they are so frustrated with managed care they will quit, retire early, or leave within three years.” This statement was a lead sentence in a newspaper article. This conclusion was based on a mail survey conductrd by the California Medical Association. Surveys were mailed to a random sample of 5000 California doctors, and 500 cornpleted surveys were returned. N!) i‘; ~ rec-{2:0 E: St: 3* riff; b. Studies linking abnormal genes to an increased risk of breast cancer are now being reevaluated. An article stated that “early studies that evaluated breast cance- risk among gene mutation carriers selected women in families where sisters, mothers, and grandmothers all had breast cancer. This created a statistical bias that skewed risk estimates for women in the general population.” . r r Efimfifiafi h' J 7. A pharmaceutical company has developed a new drug for treating high blood pressure. They would like to compare its effects to those of the most popmfig currently on the market. Two hundred volunteers with a history of high blood pressure and who are currently not on medication are recruited to participate in a study. Half of the volunteers will be randomly assigned the new drug and the other half the drug already on the market. a. Identify the explanatory van'able and the response variable if: . =~ “QM {cg d t" ‘u H {ail Jim tiara: Mel n 1‘ “ : "d .V y ,5“ 'cw. RA L glen-«i ftaggwa a)" fjfi'ofi m Mac/<3 i . b. Is this an observational study or an experiment. Explain. Be sure to put your response in context of this example. 1 xx :7: till“, Jim; at Katmai" . " t. I ’ " Erpernwr w Wilma L: ‘2vc=~!?wic’. ‘2 .. Par?!" irate}! . . . . . ., ,i c. What is the purpose of the randomizatlon? lee examples. { .15 , iii alert/swat 57,3- ‘fw; Jaimie: with igmmfi £/W-£firl‘-~~W "if; 5 I , I x .F,.=,.3 .i.‘ . ' '. l n J— Wzil mega? lie T0? “7“ lblb'vci 95?}th I, 59th or; array- Lifhgum ./ y (if fly'iit’wiaxia r d. Explain what would have to be done to make this study double—blind. p\ Vm‘ E341 (fr; Hle {Elite m odhflix‘ by“ filé'vq QTY—€1,315 1\ {Wit Carma: blfl’fi‘flffW9'fiitjf‘a €51 Maura“. do not Mam M5961 Qiacirriprc’ffiare petrified 4'5 Ffff’E/Et‘g 8. Find the z-score such that the interval within 2 standard deviations of the mean for a normal distribution contains 60% of the probability. “ ~;:-,x~- a a D. t’ Li" i — ’3: o ~2~ 9. Let the random variable X be the number of cars (including SUVs and light trucks) that American households own. The probability distribution for X is given belo‘ a." ,7: x 0 1 2 3 4 5 P(x) 0.09 0.36 0.35 0.13 0.05 0.02 , a Show that the two conditions in the definition of a probability distribution are satisfied. a} y g\ the 0‘5 WA 1‘6: aft”; #1 "' ~.~- ‘-’ .L, v r W \ J 3'\ 2H9.- ‘ .01. ..;:x¢;-, .624 e i ...
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