could somebody do question b

Printable View

- Apr 26th 2006, 06:53 PMArbiturProb Dist.. just some clarity please.
could somebody do question b

- Apr 26th 2006, 08:51 PMArbitur
changed the question

- Apr 26th 2006, 09:09 PMCaptainBlackQuote:

Originally Posted by**Arbitur**

Probability of a blue on any trial is 0.8 as we are sampling with replacement,

so:

but:

Here , so:

Which since may be reduced to:

RonL - Apr 26th 2006, 09:24 PMArbitur
uhm can you explain that in words?

i need to get it to a percent number

i thought it had to be something like

mean=.8*4-3.2

standard deviation=square root of 4*.8*.2

=.64

so (SOME NUMBER)-3.2/.64 =the zscore i need to get the percentage???

that is what my book is teaching me

what number do i use - Apr 26th 2006, 09:33 PMCaptainBlackQuote:

Originally Posted by**Arbitur**

should be looking at the section that deals with the Binomial distribution.

Quote:

what number do i use

That can be simplified to the number you want:

RonL - Apr 26th 2006, 09:42 PMArbitur
thanks anyways but i have no idea how u get that ;/

ok im looking through my book and

because of a rule i cant use the z-score way and crap... but how do i know what way and numbers to use then

ok i get it now... but what if b used really big numbers... would it still work that easy? if not what would i do( cause those are easily added 2 gether) - Apr 26th 2006, 11:00 PMCaptainBlackQuote:

Originally Posted by**Arbitur**

binomial distribution; see this thread

RonL - Apr 27th 2006, 01:46 AMCaptainBlackQuote:

Originally Posted by**CaptainBlack**

be shown by reworking this problem using the normal approximation.

Here , and , so the mean number

of blues is:

The vaiance of the number of blues is:

Now we want the probability of or more blues, so we want

the critical z-score for (rounding down by

as a continuity correction):

,

Look this up in a normal table we find:

rather than the correct value of

RonL