The article “The Influence of Corrosion Inhibitor and Surface Abrasion on the Failure of Aluminum-Wired Twist-On Connections” (IEEE Trans. on Components, Hybrids, and Manuf. Tech., 1984: 20–25) reported data on potential drop measurements for one sample of connectors wired with alloy aluminum and another sample wired with EC aluminum. Does the accompanying SAS output suggest that the true average potential drop for alloy connections (type 1) is higher than that wfor EC connections (as stated in the article)? Carry out the appropriate test using a significance level of .01. In reaching your conclusion, what type of error might you have committed? [Note: SAS reports the P-value for a two-tailed test.]
Type | N | Mean | Std Dev | Std Error |
1 | 20 17.49900000 | 0.55012821 | 0.12301241 | |
2 | 20 16.90000000 | 0.48998389 | 0.10956373 | |
Variances | T DF | Prob>|T| | ||
Unequal | 3.6362 37.5 | 0.0008 | ||
Equal | 3.6362 38.0 | 0.0008 |
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Chapter 9 Solutions
Probability and Statistics for Engineering and the Sciences
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- Algal blooms can have negative effects on an ecosystem by dominating its phytoplankton communities. Gonyostomum semen is a nuisance alga infesting many parts of northern Europe. Could the overall biomass of G. semen be controlled by grazing zooplankton species? A research team examined the relationship between the net growth rate of G. semen and the number of Daphnia magna grazers introduced in test tubes. Net growth rate was computed by comparing the initial and final abundances of G. semen in the experiment, with a negative value indicative of a decrease in abundance. The table contains the findings. Number of D. magna grazers Net growth rate of G. semen 1 2 3 4 -1.9 -2.5 -2.2 -3.9 5 -4.1 6 -4.3 Click to download the data in your preferred format. Excel Minitab 14-18 Minitab18+ JMP SPSS TI R Mac-TXT PC-TXT CSV CrunchIt! Software tells that the least-squares slope is b = -0.5286 with standard error SE, = 0.1059.arrow_forwardDuring the spring of 1999, many fuel storage facilities in Serbia were destroyed by bombing. As a result, significant quantities of oil products were spilled and burned,resulting in soil pollution. The article “Mobility of Heavy Metals Originating from Bombing of Industrial Sites” (B. Škrbić, J. Novaković, and N. Miljević, Journal of Environmental Science and Health, 2002:7–16) reports measurements of heavy metal concentrations at several industrial sites in June 1999, just after the bombing, and again in March of 2000. At the Smederevo site, on the banks of the Danube River, eight soil specimens taken in 1999 had an average lead concentration (in mg/kg) of 10.7 with a standard deviation of 3.3. Four specimens taken in 2000 had an average lead concentration of 33.8 with a standard deviation of 0.50. Find a 95% confidence interval for the increase in lead concentration between June 1999 and March 2000.arrow_forwardPlease help me with this problem and i needed only part d and e only please.... Very urgentarrow_forward
- The article "Application of Analysis of Variance to Wet Clutch Engagement" (M. Mansouri, M. Khonsari, et al., Proceedings of the Institution of Mechanical Engineers, 2002:117-125) presents the following fitted model for predicting clutch engagement time in seconds (y) from engagement starting speed in m/s (x1), maximum drive torque in N · m (x2), system inertia in kg · m² (x3), and applied force rate in kN/s (x4): y = -0.83 + 0.017.x, + 0.0895x, + 42.77.xz + 0.027x, – 0.0043x,x, The sum of squares for regression was SSR = 1.08613 and the sum of squares for error was SSE = 0.036310. There were 44 degrees of freedom for error. Predict the clutch engagement time when the starting speed is 20 m/s, the maximum drive torque is 17 N·m, the system inertia is 0.006 kg · m², and the applied force rate is 10 kN/s. b. Is it possible to predict the change in engagement time associated with an increase of 2 m/s in starting speed? If so, find the predicted change. If not, explain why not. Is it…arrow_forward4. Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying table (based on data from “Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme”, by MacGregor et al., BMJ, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril has an effect on systolic blood pressure? Explain why statistical methods from Z-interval, Z-test, T-interval or T-test –cannot be used for this problem. Then, use the sign test to conduct the required test in R studio. Please show your work.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_forward
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