CRE 考试专区

gykhl

在准备CRE考试，想开辟一个专区，把自己平时遇到的问题，分享出来，请论坛前辈不吝赐教。
如果有会做的，不光请给出结论，最重要的是给出解答过程。感谢！共同进步

今天给出问题是：

该试题来自于CRE题库，对应的是章节是CREHandbookpart2：ProbabilityandStatistics
forReliability

1.AnMBAclassprojectrequiresyourteamtoestimatetheproportionofpeoplethatwillvoteinthenextelection.Youhavenopriorknowledgeofhowmanyareexpectedtovote.Inordertoassureanestimatethatfallswithinfivepercentagepointsoferror,howmanypeopledoyouandyourteamhavetosurveytoachievethisestimatewith95%confidence(assumeNormalapproximationapplies)?
        385people


        271people


        73people


aminimumof30peopleisrecommended

2.Ifthecorrelationbetweenafactorandaresponseinasimplelinearregressionanalysisisestimatedtober=-0.90,thenthepercentofvariationintheresponsethatisattributableto(explainedby)thefactorunderstudyis:
81%


90%


10%


19%

gykhl

再加一道题，关于假设检验的，谁知道使用哪个理论做这个题？

gykhl

关于这个defectrate计算的，我算出来的是第一个，有不同答案的吗？

gykhl

有懂贝叶斯理论的可以做这个题：

wr34

你的题库是哪里来的啊ASQ的吗？

gykhl

wr34发表于2015-1-610:45
你的题库是哪里来的啊ASQ的吗？

论坛有你搜索一下

wr34

gykhl发表于2015-1-617:22
论坛有你搜索一下

你这是什么题目啊？我在想要不要买ASQ的题库
http://asq.org/training/certified-reliability-engineer-question-bank_QBCREASQ.html&item=QBCREASQ

gykhl

wr34发表于2015-1-708:08
你这是什么题目啊？我在想要不要买ASQ的题库
http://asq.org/training/certified-reliability-engine...

可以买一套，
记得给大家分享啊哈哈

gykhl

关于MTBF的计算，下面几道题感觉有点蹊跷，给位帮忙澄清一下：
Duringtheirusefullife,30unitsweretestedfor100hours.Duringthistimeperiod,5unitsfailedat10,15,30,60,and85hoursandwerenotrepaired.Whatisthefailurerate?
0.025failureperhour


0.001failureperhour


0.0019failureperhour


0.0020failureperhour



        Duringtheirusefullife,40unitsweretestedfor50hours.Duringthistimeperiod,5unitshadfailedat20,25,33,42,and45hoursbutwereimmediatelyrepairedandcontinuedinthetest.Whatisthemeantimebetweenfailures(MTBF)?
        33hours

       
        367hours

       
        383hours

       
        400hours

Duringtheirusefullife,200unitsweretestedfor50hoursandnotreplacedwhentheyfailed.Attheendofthetesttherewere10failures.Whatisthe100-hourreliabilityofthisunit?
0.900


0.903


0.905


0.950






       

gykhl

再加一个，关于可可用性的，貌似算出来没有答案中的啊哈哈
Whatistheaveragedowntimeforasystemwithdesignlifeof2,000daysofoperation,withmeantimebetweenpreventivemaintenanceof100daysandwiththefollowingdowntimemetrics?
Meanpreventivemaintenancetime=2days
Meantimetorepair=2.5days
Expectedno.offailuresoverthedesignlifeis10.
2.25days


2.0days


2.5days


10days