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In the article “Bactericidal Properties of Flat Surfaces and Nanoparticles Derivatized with Alkylated Polyethylenimines” (J. Lin, S. Qiu, et al., Biotechnology Progress, 2002:1082–1086), experiments were described in which alkylated polyethylenimines were attached to surfaces and to nanoparticles to make them bactericidal. In one series of experiments, the bactericidal efficiency against the bacterium E. coli was compared for a methylated versus a nonmethylated polymer. The mean percentage of bacterial cells killed with the methylated polymer was 95 with a standard deviation of 1, and the mean percentage of bacterial cells killed with the nonmethylated polymer was 70 with a standard deviation of 6. Assume that five independent measurements were made on each type of polymer. Find a 95% confidence interval for the increase in bactericidal efficiency of the methylated polymer.
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- An article in the Journal of the Electrochemical Society (Vol. 139, No. 2, 1992, pp. 524–532) describes anexperiment to investigate the low-pressure vapor deposition of polysilicon. The experiment was carried outin a large-capacity reactor at Sematech in Austin, Texas. The reactor has several wafer positions, and fourof these positions are selected at random. The response variable is film thickness uniformity. Threereplicates of the experiment were run, and the data are as follows:a. Test the significance of these wafer position with α=0.05.b. If proven significant, perform a multiple comparison method using Fisher’s LSD.arrow_forwardLow-Birth-Weight Hospital Stays. Data on low-birthweight babies were collected over a 2-year period by 14 participating centers of the National Institute of Child Health and Human Development Neonatal Research Network. Results were reported by J. Lemons et al. in the on-line paper “Very Low Birth Weight Outcomes of the National Institute of ChildHealth and Human Development Neonatal Research Network” (Pediatrics, Vol. 107, No. 1, p. e1). For the 1084 surviving babies whose birth weights were 751– 1000 grams, the average length of stay in the hospital was 86 days, although one center had an average of 66 days and another had an average of 108 days. a. Can the mean lengths of stay be considered population means? Explain your answer.b. Assuming that the population standard deviation is 12 days, determine the z-score for a baby’s length of stay of 86 days at the center where the mean was 66 days.c. Assuming that the population standard deviation is 12 days, determine the z-score for a…arrow_forwardThe authors of the article “Predictive Model for PittingCorrosion in Buried Oil and Gas Pipelines”(Corrosion, 2009: 332–342) provided the data on whichtheir investigation was based.a. Consider the following sample of 61 observations onmaximum pitting depth (mm) of pipeline specimensburied in clay loam soil. 0.41 0.41 0.41 0.41 0.43 0.43 0.43 0.48 0.480.58 0.79 0.79 0.81 0.81 0.81 0.91 0.94 0.941.02 1.04 1.04 1.17 1.17 1.17 1.17 1.17 1.171.17 1.19 1.19 1.27 1.40 1.40 1.59 1.59 1.601.68 1.91 1.96 1.96 1.96 2.10 2.21 2.31 2.462.49 2.57 2.74 3.10 3.18 3.30 3.58 3.58 4.154.75 5.33 7.65 7.70 8.13 10.41 13.44Construct a stem-and-leaf display in which the twolargest values are shown in a last row labeled HI.b. Refer back to (a), and create a histogram based oneight classes with 0 as the lower limit of the firstclass and class widths of .5, .5, .5, .5, 1, 2, 5, and 5,respectively.c. The accompanying comparative boxplot fromMinitab shows plots of pitting depth for four differenttypes of soils.…arrow_forward
- The article “Hydrogeochemical Characteristics of Groundwater in a Mid-Western CoastalAquifer System” (S. Jeen, J. Kim, et al., Geosciences Journal, 2001:339–348) presentsmeasurements of various properties of shallow groundwater in a certain aquifer system inKorea. Following are measurements of electrical conductivity (in microsiemens percentimeter) for 23 water samples.2099 528 2030 1350 1018 384 14991265 375 424 789 810 522 513488 200 215 486 257 557 260461 500Find the mean.Find the standard deviation.Find the median.Construct a dotplot.Find the 10% trimmed mean.Find the first quartile.Find the third quartile.Find the interquartile range.Construct a boxplot.Which of the points, if any, are outliers?If a histogram were constructed, would it be skewed to the left, skewed to the right, orapproximately symmetric?arrow_forwardThe article “Drift in Posturography Systems Equipped with a Piezoelectric Force Platform: Analysis and Numerical Compensation” (L. Quagliarella, N. Sasanelli, and V. Monaco, IEEE Transactions on Instrumentation and Measurement, 2008: 997–1004) reported the results of an experiment to determine the effect of load on the drift in signals derived from a piezoelectric force plate. The correlation coefficient y between output and time under a load of 588 N was −0.9515. Measurements were taken 100 times per second for 300 seconds, for a total of 30,000 measurements. Find a 95% confidence interval for the population correlation ρ.arrow_forwardAn article in Knee Surgery, Sports Traumatology, Arthroscopy, "Arthroscopic meniscal repair with an absorbable screw: results and surgical technique," (2005, Vol. 13, pp. 273-279) cites a success rate of 1% for meniscal tears with a rim width of less than 3 mm, and a 1% success rate for tears from 3-6 mm. If you are unlucky enough to suffer a meniscal tear of less than 3 mm on your left knee, and one of width 3-6 mm on your right knee, what is the probability that you have exactly one successful surgery? assume surgieries are independent.arrow_forward
- An article in Sensors and Actuators A: Physical [“Characterization and Simulation of Avalanche PhotoDiodes for Next-Generation Colliders” (2011, Vol. 172(1), pp. 181–188)] considered an avalanche photodiode (APD) to detect charged particles in a photo. The number of arrivals in each detection window was modeled with a Poisson distribution with a mean depending on the intensity of beam. For one beam intensity, the number of electrons arriving at an APD follows a Poisson dis- tribution with a mean of 1.74 particles per detection window of 200 nanoseconds. a. What is the mean and variance of the time for 100 arrivals?b. What is the probability that the time until the fifth particle arrives is greater than 1.0 nanosecond?arrow_forwardA golf tee manufacturer used a robot to hit balls off of their tee and a competitor's tee using the same club. Assume that 101balls were hit off each tee, and the data are suitable for inference. Is there evidence that balls hit off the manufacturer's tee have a higher initial velocity? (Assume a significance level of 0.05.) Distance (yards) Distance (yards) Ball Velocity (mph) Ball Velocity (mph) Club Velocity (mph) Club Velocity (mph) Avg. SD Avg. SD Avg. SD Competition 220.05 2.02 124.11 0.85 90.82 0.44 Manufacturer 222.28 2.57 125.37 0.41 90.82 0.44 a) Compute the t-statistic. t=_____ (Round to three decimal places as needed.) b)Compute the P-Value P-Value=_____ (Round to three decimal places as needed.)arrow_forwardSuppose a researcher is interested inthe effectiveness in a new childhood exercise program implemented in a SRS of schools across a particular county. In order to test the hypothesis that the new program decreases BMI (Kg/m2), the researcher takes a SRS of children from schools where the program is employed and a SRS from schools that do not employ the program and compares the results. Assume the following table represents the SRSs of students and their BMIs. Student intervention group BMI (kg/m2) Student control group BMI (kg/m2) A 18.6 A 21.6 B 18.2 B 18.9 C 19.5 C 19.4 D 18.9 D 22.6 E 24.1 F 23.6 A) Assuming that all the necessary conditions are met (normality, independence, etc.) carry out the appropriate statistical test to determine if the new exercise program is effective. Use an alpha level of 0.05. Do not assume equal variances.B) Construct a 95% confidence interval about your estimate for the average difference in BMI between the groups.arrow_forward
- An article in Knee Surgery, Sports Traumatology, Arthroscopy (2005, Vol. 13, pp. 273-279) considered arthroscopic meniscal repair with an absorbable screw. Results showed that for tears greater than 25 millimeters, 14 of 18 (78%) repairs were successful, but for shorter tears, 22 of 30 (73%) repairs were successful. A doctor would like to know if there is evidence that the success rate is greater for longer tears. The P-value for the test H0: p1 = p2 versus H1: p1 > p2 is closest to:arrow_forwardThe article “Study on the Life Distribution ofMicrodrills” (J. of Engr. Manufacture, 2002: 301–305) reported the following observations, listed inincreasing order, on drill lifetime (number of holesthat a drill machines before it breaks) when holes weredrilled in a certain brass alloy. 59 61 65 67 68 71 74 76 78 7981 84 85 89 91 93 96 99 101 104105 105 112 118 123 136 139 141 148 158161 168 184 206 248 263 289 322 388 513a. Why can a frequency distribution not be based onthe class intervals 0–50, 50–100, 100–150, andso on?b. Construct a frequency distribution and histogram ofthe data using class boundaries 0, 50, 100, … , andthen comment on interesting characteristics.c. Construct a frequency distribution and histogram ofthe natural logarithms of the lifetime observations,and comment on interesting characteristics.d. What proportion of the lifetime observations in thissample are less than 100? What proportion of theobservations are at least 200?arrow_forwardThe Lion’sMane. In a study by P. M.West titled “The Lion’s Mane” (American Scientist, Vol. 93, No. 3, pp. 226–236), the effects of the mane of a male lion as a signal of quality to mates and rivals was explored. Four life-sized dummies of male lions provided a tool for testing female response to the unfamiliar lions whose manes varied by length (long or short) and color (blonde or dark). The female lions were observed to see whether they approached each of the four life-sized dummies. a. experimental units. b. response variable. c. factor(s). d. levels of each factor. e. treatments.arrow_forward
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