t2_ans_sta2023-86728_20110321_p11

t2_ans_sta2023-86728_20110321_p11 - TALLAHASSEE COMMUNITY...

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Unformatted text preview: TALLAHASSEE COMMUNITY COLLEGE LAST M— FIRST ___._.__._....._- 5TA2023—86728 I SPRING 2011 TEST #2: Mon.03.21.11 SECTS 2.5, 2.6, 3.1-3.4, 4.1-4.4, 5.1-5.3 - A&F 2"d INSTRUCTOR: D. Jones lNSTRUCTIONS: Do all your work on this test paper. You may use your calculator. You may do your “scrap-work” on this test. But BOX your final answers neatly in the space provided, unless there is already a BOX. Thank You, a nd Good Luck! ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1. (10: 2 ea. ). The carbon dioxide emission levels of a group of nations has a mean of 9.8 and a standard deviation of 1.7. 33:9}? 5 4' la? (A) Write the formula for a z—score: ’ - ‘ -: 3 (B) One country has an emission level of 14.9. )t— : H's“? £: h ? (i) Find the — re. (Round to two decimal places as needed). - I: 3 (ii) Is the emission level of 14.9 an outlier? Why or why not? =19 H6 j if :5 wttlim 3 sni- dcv‘ cg the mean. (C) Another country has an emission level of 3.7. jaw -— 3, 59 (i} Fin - nd to two decimal places as needed). l" 7' l z—a: « 3:59 (ii) Is he emission level of 3.7 an outlier? Why or why not? 'Yts il’ ‘3 L19? wl'ifii‘n 3 s‘lddev. at»? the mean. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2. l 10: 1 ea. up to 10}. A survey asked “Do you believe in heaven?” and “Do you believe in hell?” 835 subjects answered “yes” to both questions, 160 answered “no” to both, 124 answered “yes” to heaven but “no” to hell, and 3 answered “no” to heaven but “yes” to hell. (A) Display the data as a contingency table: l Do you believe in heaven? | Do you believe in hell? | Yes I No Total Yes 3 338 (E) Find the conditional proportions that treat opinion about heaven as the response variable and opinion about hell as the explanatory variable. Do you believe in heaven? | Do you believe in hell? No Total | of 003 e 0 i ‘36 ’54 (Round to four decimal places as needed). ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3;20;2011 9:44 PM test_02_sta2023-86728v-01_p11.dOCJ( page 1 of 4 . 3. (10: 5,5 ). The percent of the population in a country that uses cell phones can be predicted using 3? = —O.‘l 5 + 2.66x where y is the percentage of the pOpulation that uses cell phones and x is gross domestic product (GDP) in thousands of dollars per capita. L 'J.) 2, ' (A) If the GDP is 0.7, predict the percentage of the population that uses cell phones. 1'1“ 2'3 9"93‘ (B) If the GDP is 34.6, predict the percentage ofthe population that uses cell phones. 1' 89 9O _ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 4. (10:4,4,2). 60 people with severe headaches are randomly divided into two groups. One group is treated weekly with relaxing music and an exercise regimen. The other is treated weekly with exactly the same exercise regimen, but no relaxing music. After one year, both groups are questioned about their severe headaches. (A) The response variable is sevegg hfidfldfifid the explanatory variable is retaxmg music . (B) Choose the correct description of the study — put a check-mark for the answer of your choice (v) ( ). The study is an observational study because the researchers only observe values of the response and explanatory variables. ( ). The study is an observational study because the researchers cannot control the response variable after one year. ( ). The study is an experimental study because the researchers cannot control the response variable after one yea r. (V). The study is an experimental study because the researchers assign subjects to certain experimental conditions and observe the outcomes on the response variable. ~~++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 5. (10:1,3,3,3). A 2004 poll reported that 69% of people worried that they would be exposed to SARS (Severe Acute Res irato Syndrome). , p w Zdeamis (A) What is the formula for Approximate Margin of Error? AM E = 4—- 3 (00’, JF' (B) Find the approximate margin oferror if: (i) n = 79 (ii) n : 392 (iii) n : 1347 IE3 2» ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 6. (10:4,4,2). A randomized experiment investigates whether an herbal treatment is better than a placebo in treating subjects suffering from depression. Unknown to the researchers, the herbal treatment has no effect: Subjects have the same score on a rating scale for depression (for which higher scores represent worse depression) no matter which treatment they take. After ta king the assigned treatment for 3 months, subjects’ scores on the depression scale are as follows. " number Response: Depression 84 Level sum“ 1 i 2 i 3 4 i 5 i 6 i 7 i 8 46 56 46 48 82 69 (continued, next page) 3/20,!2011 9:44 PM test_02_sta2023-86728v—01__p11.docx page 2 of 4 . (A) Based upon the treatment assignment given below, find the sample mean response for those who took the herbal supplement and for those who took the placebo. Treatment Herbal Subjects Sample Mean (Answer as an integer or a decimal rounded to the nearest hundredth as needed) (B) Can sample means vary even when there is "no effect?”Why? Yes... Due it» 5M3?“ sample S;&I(n:53 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 7. (15:5,5,5). The contingency table below shows results from a study about whether there was an association between mobile phone use and eye cancer. Eye Cancer and Use of Mobile Phones Mobile Phones l Cases Controls I‘D-[E’- _ 4.33 @- (A) The study was retrospective. Explain in one sentence what this means. _ . . _ e“. mugem “Rffims eth-Ftu meant; .thai e-Sfai'cma’s WE fimeectS (lb!) Lil- fl" P mum? Pkg-3t Lust [1“: Wet. tail hlsbflin (B) “Cases” refer to subjects who had eye cancer, and “controls” refer to subjects who did not have eye cancer. (1] What proportion has used mobile phones, of those in the study who hadueye cancer? (Round off to the nearest hundredth as needed). “fa—nua— The proportion is: {2) What proportion had used mobile phones, of those in the study who did not have eye cancer? (Rou nd off to the nearest hundredth as needed}. The proportion is: -+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3:20:2011 9:44 PM test_02_sta2023-35728u-01_p11.docx page 3 of 4 . 8. (15:5,5,5 ). A local shop found from past observations that 90% of the people who enter the shop actually buy something. Three potential customers enter the shop. (A) Let S = Sale and N = No Sale. What is the probability that a customer buys and a sale is made? P(S]: 0.20 And what is the probability that a customer does not buy? PfN) = 0: M {B} Complete the tree diagram, assuming that the successive events are independent. 5 (.9) 5 (.9) insert the value of PlS) into the ( ). S (a?) N (a) S (49') N (,r) 5 (.3) N CA) N (,1) I n (3) N (a) ‘- ———— N (,1) FindP(A)= l--- P(A‘):|-—~ (.l a. s (.9) start (C) Let A be the event “making at least one sale.” (Round to three decimal places as needed). urnament, the winner of the event ma fher first serves. When she faulted on 9. (10). In a women’s tenni her first serve, she mad 90% fher second serves. Aswming these are ypical of her serving performance, when she serves, what is the pr abilityr that she makes a double fault? PM)a .-2ox .10 ~: ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++J¢E++++++H++++++++++++++++++ ' 80% Bonus (5}: In our textbook, what do the initials DDI stand for? D: Design 312012011 9:44 PM testm02_st32023‘85728v-01_p11.docx page 4 of a . ...
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This note was uploaded on 12/30/2011 for the course STA 2023 taught by Professor Jones during the Spring '11 term at Tallahassee Community College.

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t2_ans_sta2023-86728_20110321_p11 - TALLAHASSEE COMMUNITY...

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