304_Exm2_07_forWeb - CEE 304 - Uncertainty Analysis in...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
CEE 304 - Uncertainty Analysis in Engineering Second Examination November 9, 2007r You may use text, your notes and calculators. There are 50 points in total, one per minute. Show work 1. (12 pts) A structural engineer needs to model the cumulated stress on the landing gear of an airplane design. Aging airplanes pose a risk of failure. The cumulated metal fatigue depends upon F the product of the landing-weight W times the vertical-landing-speed S, so that F = W•S. She needs the whole F distribution. Assume that W and S are independent random variables with lognormal distributions. W has a mean of 120 with a coefficient of variation of 0.20. S has a mean of 35 with a standard deviation of 12. (a) What is the 95 percentile of the S distribution? (b) What are the mean and variance of the F distribution? 2. (6 pts) A geotechnical engineer needs to evaluate the properties of soil around a construction site. He instructs his technician to collect 10 samples. However, the technician is lazy, and also dishonest (and a little stupid). The technician collects 6 samples, and then adds the four fixed values 50, 54, 56, and 60. Suppose measurements of the soil parameter really have a gamma distribution with a mean μ of 62 and a stand. deviation of 9. If the engineer computes the sample average A of the ten values [6 measurements, and 4 fixed values], what is the mean square error of his estimator of μ: A = [ X 1 + X 2 + X 3 + X 4 + X 5 + X 6 + 50 + 54 + 56 + 60]/10 ? 3. (6 pts) A biochemical engineer has the responsibility to ensure that an unwanted contaminant does not
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

304_Exm2_07_forWeb - CEE 304 - Uncertainty Analysis in...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online