Bivariate data often arises from the use of two different techniques to measure the same quantity. As an example, the accompanying observations on x = hydrogen concentration (ppm) using a gas chromatography method and y = concentration using a new sensor method were read from a graph in the article “A New Method to Measure the Diffusible Hydrogen Content in Steel Weldments Using a Polymer Electrolyte-Bused Hydrogen Sensor” (Welding Res., July 1997: 251s–256s).
x | 47 | 62 | 65 | 70 | 70 | 78 | 95 | 100 | 114 | 118 |
y | 38 | 62 | 53 | 67 | 84 | 79 | 93 | 106 | 117 | 116 |
x | 124 | 127 | 140 | 140 | 140 | 150 | 152 | 164 | 198 | 221 |
y | 127 | 114 | 134 | 139 | 142 | 170 | 149 | 154 | 200 | 215 |
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Chapter 12 Solutions
Probability and Statistics for Engineering and the Sciences
- Structural engineers use wireless sensor networks to monitor the condition of dams and bridges. The article "Statistical Analysis of Vibration Modes of a Suspension Bridge Using Spatially Dense Wireless Sensor Network" (S. Pakzad and G. Fenves, Journal of Structural Engineering, 2009:863-872) desaribes an experiment in which accelerometers were placed on the Golden Gate Bridge for the purpose of estimating vibration modes. For 18 vertical modes, the system was underdamped (damping ratio 1)? Explain why or why not f. e. For what damping ratio would you predict a frequency of 2.0?arrow_forwardWire electrical-discharge machining (WEDM) is a process used to manufacture conductive hard metal components. It uses a continuously moving wire that serves as an electrode. Coating on the wire electrode allows for cooling of the wire electrode core and provides animproved cutting performance. The article “High-Performance Wire Electrodes for Wire Electrical-Discharge Machining—A Review” (J. of Engr. Manuf.,2012: 1757–1773) gave the following sample observationson total coating layer thickness (in mm) of eightwire electrodes used for WEDM:21 16 29 35 42 24 24 25Calculate a 99% CI for the standard deviation of thecoating layer thickness distribution. Is this interval validwhatever the nature of the distribution? Explain.arrow_forwardAn article in Environment International ["influence of Water Temperature and Shower Head Office Size on the release Radon During Showering" (1992, Vol. 18(4)] described an experiment in which the amount of radon released in showers was imvestigated. Radon-enriched water was used in the experiment, and six different orifice diameters were tested in shower heads. The data from the experiment are shown in the following table. 5. Orifice Diameter 0.37 0.51 0.71 1.02 Radon Released () 83 75 73 72 83 85 79 79 74 76 77 67 74 74 1.40 62 62 67 69 1.99 60 64 66 (a) Does the size of the orifice affect the mean percentage of radon released? Use a=0.05. (b) Find a 95% confidence interval on the mean percent of radon released when the orifice diameter is 1.40.arrow_forward
- The cetane number is a critical property in specifying the ignition quality of a fuel used in a diesel engine. Determination of this number for a biodiesel fuel is expensive and time- consuming. The article "Relating the Cetane Number of Biodiesel Fuels to Their Fatty Acid Composition: A Critical Study" (J. of Automobile Engr., 2009: 565–583) included the following data on x = iodine value (g) and y = cetane number for a sample of 15 biofuels The iodine value (x) is the amount of iodine necessary to saturate a sample of 100 g of oil. The article's authors fit the simple linear regression model to this data, so let' s does the same. 132.0 129.0 120.0 113.2 105.0 92.0 84.0 88.4 59.0 80.0 81.0 81.5 71.0 69.2 63.0 y 46.0 48.0 51.0 52.1 54.0 52.0 59.0 58.7 61.6 64.0 61.4 54.6 58.8 58.0 51.4 Construct a scatter plot for the data. Identify and state which is dependent and independent variable. What is the purpose of the scatter plot/diagram? 2. Fit a simple linear regression line/ equation to…arrow_forwardThe cetane number is a critical property in specifying the ignition quality of a fuel used in a diesel engine. Determination of this number for a biodiesel fuel is expensive and time- consuming. The article "Relating the Cetane Number of Biodiesel Fuels to Their Fatty Acid Composition: A Critical Study" (J. of Automobile Engr., 2009: 565–583) included the following data on x = iodine value (g) and y = cetane number for a sample of 15 biofuels The iodine value (x) is the amount of iodine necessary to saturate a sample of 100 g of oil. The article's authors fit the simple linear regression model to this data, so let' s does the same. 132.0 129.0 120.0 113.2 105.0 92.0 84.0 88.4 59.0 80.0 81.0 81.5 71.0 69.2 63.0 y 46.0 48.0 51.0 52.1 54.0 52.0 59.0 58.7 61.6 64.0 61.4 54.6 58.8 58.0 51.4 3) Estimate the correlation coefficient (Pearson coefficient), r, between x and y and explain briefly the strength of r and its direction and comment the p-value. 4) Construct a 95% two-sided confidence…arrow_forwardIn the article “Groundwater Electromagnetic Imaging in Complex Geological and Topographical Regions: A Case Study of a Tectonic Boundary in the French Alps” (S. Houtot, P. Tarits, et al., Geophysics, 2002:1048–1060), the pH was measured for several water samples in various locations near Gittaz Lake in the French Alps. The results for 11 locations on the northern side of the lake and for 6 locations on the southern side are as follows: Northern side: 8.1 8.2 8.1 8.2 8.2 7.4 7.3 7.4 8.1 8.1 7.9 Southern side: 7.8 8.2 7.9 7.9 8.1 8.1 Find a 98% confidence interval for the difference in pH between the northern and southern side.arrow_forward
- Foot ulcers are common problem for people with diabetes. Higher skin temperatures on the foot indicate an increased risk of ulcers. The article “An Intelligent Insole for Diabetic Patients with the Loss of Protective Sensation" (Kimberly Anderson, M.S. Thesis, Colorado School of Mines), reports measurements of temperatures, in °F, of both feet for 18 diabetic patients. The results are presented in the Table QI. Table Q1: Measurements of temperatures, in °F of left foot Vs right foot for 18 diabetic patients Left Foot 80 foo Right Foot Right Foot 81 Left Foot (a) berature m80 85 76 85 89 86 9 marks) 75 80 87 82 88 foot temper 86sof 89 would thei 87 ht foo temp 80ures will 78s differ by 278reespredict by 81 (b) 87 82 87 82 I marks) 78 right foot to9erature for 76 tient whose 0 foot tmperature 78 86 85 (c) 88 89 90 88 89 (I marks) (d) Test the slope, ß1 = 1 at 5% level of significance. (e) Calculate the coefficient of correlation r and r² and then interpret their valuesarrow_forwardThe removal of ammoniacal nitrogen is an important aspect of treatment of leachate at landfill sites. The rate of removal (in percent per day) is recorded for several days for each of several treatment methods. The results are presented in the following table. (Based on the article "Removal of Ammoniacal Nitrogen from Landfill Leachate by Irrigation onto Vegetated Treatment Planes," S. Tyrrel, P. Leeds-Harrison, and K. Harrison, Water Research, 2002:291–299.) Treatment Rate of Removal 5.21 4.65 5.59 2.69 7.57 5.16 6.24 5.94 6.41 6.85 9.18 4.94 4.04 3.29 4.52 3.75 Construct an ANOVA table. You may give a range for the P-value. Can you conclude that the treatment methods differ in their rates of removal? a. b. ABCAEarrow_forwardThe decline of salmon fisheries along the Columbia River in Oregon has caused great concern among commercial and recreational fishermen. The paper 'Feeding of Predaceous Fishes on Out-Migrating Juvenile Salmonids in John Day Reservoir, Columbia River' (Trans. Amer. Fisheries Soc. (1991: 405-420) gave the accompanying data on y = maximum size of salmonids consumed by a northern squaw fish (the most abundant salmonid predator) and x = squawfish length, both in mm. Here is the computer software printout of the summary: Coefficients: Estimate Std. Error t value Pr(> |t|) (Intercept) −89.010 16.703 −5.329 0.000 Length 0.705 0.046 15.293 0.000 Using this information, give the equation of the least squares regression line.arrow_forward
- A new design for the braking system on a certain type of car has been proposed. For the current system, the true average braking distance at 40 mph under specified conditions is known to be 120 ft. It is proposed that the new design be implemented only if sample data strongly indicates a reduction in true average braking distance for the new design. (a) Define the parameter of interest. O μ = true average braking distance for the new design O p = true proportion of cars whose braking distances did not reduce O p = true proportion of cars whose braking distances reduced O μ = true average braking distance for the old design State the relevant hypotheses. Ho: μ = 120 H₂: μ = 120 O Ho: p = 120 Ha: p 120 ⒸHo: μ = 120 H₂: μ< 120 O Ho: p = 120 H₂: p = 120 ✔ (b) Suppose braking distance for the new system is normally distributed with = 13. Let X denote the sample average braking distance for a random sample of 36 observations. Which values of X are more contradictory to Ho than 117.2? O x ≥…arrow_forward5.1 Byers and Williams (Viscosities of Binary and Ternary Mixtures of Polyaromatic Hydrocarbons," Journal of Chemical and Engineering Data, 32, 349 – 354, 1987) studied the impact of temperature (the regressor) on the viscosity (the response) of toluene- tetralin blends. The following table gives the data for blends with a 0.4 molar fraction of toluene. Temperature (°C) Viscosity (mPa·s) 24.9 1.133 35.0 0.9772 44.9 0.8532 55.1 0.7550 65.2 0.6723 75.2 0.6021 85.2 0.5420 95.2 0.5074 c. Basic principles of physical chemistry suggest that the viscosity is an exponential function of the temperature. Repeat part b using the appropriate transformation based on this information.arrow_forward5.1 Byers and Williams (Viscosities of Binary and Ternary Mixtures of Polyaromatic Hydrocarbons," Journal of Chemical and Engineering Data, 32, 349 – 354, 1987) studied the impact of temperature (the regressor) on the viscosity (the response) of toluene- tetralin blends. The following table gives the data for blends with a 0.4 molar fraction of toluene. Temperature (°C) Viscosity (mPa·s) 1.133 24.9 35.0 0.9772 44.9 0.8532 55.1 0.7550 65.2 0.6723 75.2 0.6021 85.2 0.5420 95.2 0.5074 b. Fit the straight line model. Compute the summary statistics and the residual plots. What are your conclusions regarding model adequacy?arrow_forward
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