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Unformatted text preview: ln(1000) + ML VL , ML 2 + VL 2 ] = N[1.18, 0.078] Now: E[C] = exp[ CL + 0.5 CL 2 ] = 0.318 mg/l ; Coef. of Var. C = exp( CL 2 )-1 = 0.286 3. A structural engineer believes that the compressive strength C of some concrete columns supporting a very long bridge is distributed with a mean of 8000 psi and a standard deviation of 1500 psi. Compute c d , which is the strength exceeded by 95% of these columns, based on the following distributions: a.) Normal Distribution b.) Lognormal Distribution c.) Gamma Distribution d.) Gumbel Distribution e.) Weibull Distribution [with k = 6.22, (1 + 1 / k ) = 0.9295] Ans . c d is the 5 th percentile (x 0.05 ) a.) Normal Distribution x 0.05 = 5532.5 psi b.) Lognormal Distribution x 0.05 = 5790.8 psi c.) Gamma Distribution x 0.05 = 5700 psi[using Excel] d.) Gumbel Distribution x 0.05 = 6041.7 psi e.) Weibull Distribution [with k = 6.22, (1 + 1 / k ) = 0.9295] x 0.05 = 5339 psi...
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This note was uploaded on 02/02/2008 for the course CEE 3040 taught by Professor Stedinger during the Fall '08 term at Cornell University (Engineering School).
- Fall '08