Exam 3 with Answer Key - Business Statistics | BMGT 230, Exams of Business Statistics

Download Exam 3 with Answer Key - Business Statistics | BMGT 230 and more Exams Business Statistics in PDF only on Docsity! Business Statistics, BMGT23 0 Fall2007 Studer-Ellis Examination 3 14 November 2007 COPY Z ANSWER KEY Please provide the information requested below and on the next page SHOW aII relevant work When necessary, carry values out to at least three (3) decimal places. Good Luck! Last Name (print): First Name (print): Honor Code Signature: Course & Section: BMGT 230 Print Name: Fall2007 lz. Holding all other values constant, does the range of sample values INCREASE, DECREASE, or REMAIN THE SAME (CJRCLE one) when the sample size decreases? (3 points) jl^rnrto 5,ttz do.,Q-,/D/ '+t''L f ,r,\p o( i--.41\u vq\utz A l>e )':Q.*'ts. 2z.The U.S. Department of Transportation reported recently that all commuters in the Washington, DC area average 120 minutes on the road traveling to and from work each workday. Assume that the standard deviation for the amount of time all commuters in the Washington, DC area travel to and from work each workday equals 30 minutes (work REQUIRED for each part). a.If a random sample of 36 commuters in the Washington, DC area is selected, calculate the associated standard error of the mean. (5 points) f ,. \Lo n'- 9u v --\a $r"')<'t c{rtt glaa)! dc,Jitl,c:4 b. What is the probability that mean travel time for the commuters in points) Examination 3 Course & Section: UN COPY Z 9 _, ic,?g 6'e *5 the sample is less than 122.5 mirnttes? (5 /z la:- 6 ^ t1o ff Lz<,s) , 5 .l , lql{ -. , Lql€ 32. A study byDecision Analysts shows that 0.20 of all individuals who use credit cards are very close to the limits on their cards. To determine the probability that more than 0.25 of the users in the sample are very close to the limits on their cards, you select a random sample of 600 individuals who use credit cards. Calculate the associated standard error of the proportion. (work REQUIRED for credit; 5 points) --Lgu Jnludlu ullul uI Luv PruPUrLlvrr. \wvrA rw\<vuwv lul vrwslL) J yvtrrlJ) -/6v"' 94qtL'r> uL/t .,1 1 ... a _-r ^ \ ''l9 i " olrtAlbtY 42. SuperPrep, & test preparation company, offers courses to help its customers increase their standardized test (for example, SAT) scores. The 90%o confidence interval estimate for the SAT math score for all SuperPrep customers after taking the course equaled 565.5 to 665.5. If the average SAT math score for all SuperPrep customers before taking the course equaled 575, use the confidence interval estimate to determine which of the following statements is true (CIRCLE the corresponding roman numeral; 5 points): i. The course did not increase the average SAT math score. S,t fne course did increase the average SAT math score, but the increase was not statistically significant. iii. The course did increase the average SAT math score, and the increase was statistically significant. iv. One can not use a confidence interval estimate to determine whether the course increase the average SAT math score significantly. 1lz. A pharmaceutical company guarantees that its new drug reduces (i.e., decreases) systolic blood pressure. To test the company's claim, a drug-testing agency selects a random sample of fifteen (15) patients with high blood pressure. The drug-testing agency measures and records the systolic blood pressure of the patients before and after taking the new drug. a. Are the samples independent or dependent? (3 points) $ur +I,o v b. State the null and alternative hypotheses associated with the test. (3 points) i I A,c4ta'€ a€t"t b'*"'''Z n{vrnA' ll ' Eth''< trcM 1'0 c. If a: 0.01, determine the critical value of the associated test statistic (include ALL relevant information and the sign or signs). (3 points) .,\ N, 11 T-21,+ ,g\ u.Yz\\'L.v1rtl( d. If the calculated value of the associated test statistic equals 1.7582, state your decision regarding the null hypothesis. (3 points) \l S t1,<rYLue Lr\LQ u(;V h, l, .rD* 122.T\e friendly folks at the Internal Revenue Service [IRS] are always looking for ways to improve the *ording and format of tax returns. Three new forms have been developed recently. To determine which new' forms, if any, are "better" than the current form, 20 individuals were asked to participate in an ANOVA study. Five different people hlled out each of the three new forms and the current form. The amount of time (in minutes) each participant took to complete the task is shown below: New Form 1 New Form 2 New Form 3 Current Form 35 55 39 48 47 38 43 57 Minutes 50 49 37 61 43 62 29 51 25 -Loo 56 -']-Lv 27 -l'){ 63'L8o Vo !,i- 4s s e a. State the null and alternative hypotlieses associated with tfiJstudy. (3 points) 'Lt-t Z ,L) L 4 J'^/ 1z "( (,v-trinf ntbttt ,r, t2 : a? t t-Zi b. Complete the following ANOVA table, based on the information above (6 points): Source Sum of Squares df Mean Square F Between 1463.75 Within 1086.00 1.1-t 'b 1t't uer' 7, lrl ao-q'lu bJ 87t iATotal 2f 4 \'16 c. If o: 0.05, what is the critical value of the associated test statistic? (3 points) 7l2 /lL ? ort ,ntL/ gz3-1 d. State your decision regarding the null hypothesis. (3 points) L ",\t' 2*1, /DL* V* e. Compare the means for the three new forms to the mean for the current form. If Tukey's HSD equals 14.92, which (if any) of the new forms are "better" than the current form ("better" means the signs of the differences between means matter)? (3 points) J , uunl'; lL I L v uqraYr4 ) n w,{/nlr2 'l-\