Probability and Statistics for Engineering and the Sciences
9th Edition
ISBN: 9781305251809
Author: Jay L. Devore
Publisher: Cengage Learning
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Chapter 9.5, Problem 65E
The article “Enhancement of Compressive Properties of Failed Concrete Cylinders with Polymer Impregnation” (J. of Testing and Evaluation, 1977: 333–337) reports the following data on impregnated compressive modulus (psi 3 106) when two different polymers were used to repair cracks in failed concrete.
| Epoxy | 1.75 | 2.12 | 2.05 | 1.97 |
| MMA prepolymer | 1.77 | 1.59 | 1.70 | 1.69 |
Obtain a 90% CI for the ratio of variances by first using the method suggested in the text to obtain a general confidence interval formula.
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Do the amount of RHA affect the compressive strength? How?
The article "Bone Density and Insertion Torque as Predictors of Anterior Cruciate Ligament Graft Fixation Strength"t gave the accompanying data on maximum insertion torque (N• m) and yield load (N), the latter being one
measure of graft strength, for 15 different specimens.
Torque
1.8
2.2
1.9
1.3
2.1
2.2
1.6
2.1
1.2
1.8
2.6
2.5
2.5
1.7
1.6
Load
491
477
598
361
605
671 466
431
384
422
554
577
642
348
446
(a) Is it plausible that yield load is normally distributed?
Yes, there are more than thirty data values.
No, a normal probability plot of yield load is not quite linear.
Yes, a normal probability plot of yield load is quite quadratic.
No, there is not more than thirty data values.
Yes, a normal probability plot of yield load is quite linear.
(b) Estimate true average yield load by calculating a confidence interval with a confidence level of 95%. (Round your answer to two decimal places.)
Interpret the interval.
We are 95% confident that the true population average yield load lies below…
What is the unit for sleep(answer: hours)? Is its skewness and kurtosis really far enough away from zero to say it is not normal? I was in the chat with two people and they could not assist. I was told to submit my question to a specialtist.
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Chapter 9 Solutions
Probability and Statistics for Engineering and the Sciences
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