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Ramp metering is a traffic engineering idea that requires cars entering a freeway to stop for a certain period of time before joining the trafc ow. The theory is that ramp metering controls the number of cars on the freeway and the number of cars accessing the freeway, resulting in a freer flow of cars, which ultimately results in faster travel times. To test whether ramp metering is effective in reducing travel times, engineers conducted an experiment in which a section of freeway had ramp meters installed on the on-ramps. The response variable for the study was speed of the vehicles. A random sample of 15 cars on the highway for a Monday at 6 pm. with the ramp meters on and a second random sample of 15 cars on a different Monday at 6 pm. with the meters off resulted in the following speeds (in miles per hour). a Click the icon to view the data sets. ' A. n" B. c. Q Q OtT_ Off_ 0n- 0' On- 9' ,..,.,..,..... ,...........,.. o 15 30 45 60 13' o 15 30 45 so l2: 0 MPH MFH Does there appear to be a difference in the speeds? 0 Speed data an MPH) A. No, the box plots do not show any difference in speeds. a" B. Yes, the Meters 0n data appear to have higher speeds. Ramp Meters 0n Ramp Meters Off FU\" D3\" 59' 9 C. Yes, the Meters Off data appear to have higher speeds. 29 47 55 25 25 43 ' 39 30 26 34 36 30 Are there any outliers? 43 41 49 46 39 20 ' 34 56 39 28 24 39 A. Yes, there appears to be a high outlier in the Meters Off data. 41 21 41 37 5o 42 B. Yes. there appears to be a low outtier in the Meters 0n data. C. Yes, there appears to be a high outlier in the Meters On data. 3 D. No, there does not appear to be any outliers. (b) Are the ramp meters effective in maintaining a higher speed on the freeway? Use the d=0.01 level of signicance. State the null and alternative hypotheses. Choose the correct answer below. 'A- Homo" = Parr 5- Home" Wow \"woman H1=uon>itcm 6- Haruon WW 0- Homo" =Paff H1:\"on > "off \"12%" lloff Determine the P-value for this test. P-value = (Round to three decimal places as needed.) A researcher wanted to determine if carpeted rooms contain more bacteria than uncarpeted rooms. The table shows the results for the number at bacteria per cubic foot for both types of rooms. Full data set 9 Carpeted Uncarpehd 10.6 12.2 14.2 5.5 7.4 7.9 8.5 13 14 9,3 112 7.6 15.1 10.8 7 11.5 Determine whether carpeted rooms have more bacteria than uncarpeted rooms at the ot= 0.05 level of signicance. Normal probability plots indicate that the data are approximately normal and boxplos indicate that there are no outliers. State the null and alternative hypotheses. Let population 1 be carpeted rooms and population 2 be uncarpeted rooms, A- Ho: P1 P2 B. H0:p1=p2 H1=P1 P2 Determine the P-value for this hypothesis test. P-value =D (Round to three decimal places as needed.) A professor wanted to determine whether an online homework system improved scores on a final exam. In the fall semester, he taught a class using the online homework system (which meant students did their homework online and received instant feedback about their answers along with helpful guidance). In the spring semester, he taught a class without the homework system which meant students were responsible for doing their homework the old-fashioned way - paper and pencil). The professor made sure to teach the two courses identically (same text, syllabus, tests, meeting time, meeting location, and so on). The table summarizes the results of the two classes on their final exam. Complete parts (a) through (e) below. Click the icon to view the table. (a) What type of experimental design is this? O A. Retrospective study O B. Prospective study O C. Randomized blocked design D. Completely randomized design (b) What is the response variable? Teacher Final exam scores O Test Location O Tex O Weather Homework system O Syllabus What are the treatments in the study? Select all that apply. O Location LY Homework system Final exam scores O Teacher Syllabus Test Text Weather (c) What factors are controlled in the experiment? Select all that apply. Location Text Syllabus Homework system Teacher Final exam scores X Tes Weather (d) In many experiments, the researcher will recruit volunteers and randomly assign the individuals to a treatment group. In what regard was this done for this experiment? A. The assumption is that the students "randomly" enrolled in the course. O B. The assumption is that the students were selected for each course. O C. The assumption is that the students knew about the experiment and choose to be in one of the two classes. O D. No assumptions were made for this experiment. (e) Did the students perform better on the final exam in the fall semester? Use an a = 0.01 level of significance. State the null and alternative hypotheses. O A. Ho: Hfall > Hspring B. Ho: Hfall = Hspring i Summary data X H1: Hfall Hspring O C. Ho: Hfall = Hspring O D. Ho: Hfall = Hspring H1: Hfall Hspring Hy: Hfall