jackhzs 发表于 2013-10-8 14:53:34

请教如何计算：
31.Acomponenthasstrengthwithmeanvalueof9,000Nandstandarddeviationof900N.Ithastowithstandaloadwithmeanvalueof5,500Nandstandarddeviationof800N.
Bothstrengthandloadarenormallydistributed.Whatistheprobabilityoffailureforthecomponent?
(A)2.0×E-5
(B)1.8×E-3
(C)5.8×E-3
(D)2.0×E-2

jackhzs 发表于 2013-10-8 14:54:34

63.Acertaincomponenthasitsstrengthdistributednormallywithanaverageof20,000poundspersquareinch(psi)andastandarddeviationof1,200psi.Thestressonthecomponentisalsonormallydistributedwithanaverageof17,500psiandastandarddeviationof800psi.Onthe
basisofthisinformation,whatisthecomponent’sreliability?
(A)0.9052
(B)0.9582
(C)0.9814
(D)0.9972

weitervor 发表于 2013-10-18 14:59:44

求答案。。。谢谢！

brain.ding 发表于 2013-10-18 19:44:14

学习下，不是很懂
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