Finding sample size for 90% confidence that threshold is 99.99% correct

[sstudent]

we need to show with 90% confidence that the probability of the "treshhold number" being correct is 99.99%. "So we want P=0.9999 with C=0.90". we can consider 5 trails without put { 4, 7, 12, 9, 11}..we can say the treshhold # is the "2nd trail = 7"... i tried doing it using t alpha but i failed to get it... i haven't taken statistics in years..thanks for help folks

 

[sstudent]

is it that hard??

 

[Dick]

is it that hard??

Yes. I don't understand what you are talking about. Can you give a reference for the background to this problem?

 

[sstudent]

http://www.itl.nist.gov/div898/handbook/prc/section2/prc263.htm

this can be a reference

 

[Dick]

Ok, now can you explain what your problem is? You have five trials? You want to say the probability of something is 0.9999? The probability of what exactly?

 

[sstudent]

the probability of the treshhod # being correct, which is the 2nd trail..thanks

 

[Dick]

the probability of the treshhod # being correct, which is the 2nd trail..thanks

This isn't helping. You are just repeating what I don't understand. What do the trials represent? Are they samples from some distribution? What does it mean for one of them to be 'correct'. What is correct? What's a 'threshold'? Can you define all of these things?

 

[sstudent]

the trails are just sample from some distributaion, for the treshhold # u can say its just a numer, so we are trying to prove the the output of the samples larger than 7 "treshhold" is 99.99% with 90%confience..i hope that makes it more clear

 

[konthelion]

I believe you are talking about the tolerance interval. In this problem, your confidence level is 95% and the threshold interval for capturing at least 99.99% i.e. % of these samples falling in the tolerance interval is:
$$\bar{x} \pm (tolerance)s$$ , where tolerance is your tolerance critical value.

Your statistics book should have a tolerance critical value table.