Question on Exercise 8.6

Summary:

(by Lisa)

Question on Exercise 8.6

Vinh Tran 15 Apr 2009 11:57

Dear ser,

hi, ser
this is my question about Convidence interval for average with standard deviation unknown.
that question exactly in page 4 in tutorial exercise 8.6 and in page 271 in book.
Actually, in the question there are mention such " with 500 grams"
i though that number is the population(N)
however, why in the tutorial solution we use the first formula (for standard deviation is known)
but not use the second formula?
(if population is finite)

thanks

Re: Question on Exercise 8.6

Vinh Tran 15 Apr 2009 12:06

Hi Lisa,

The population is the total number of bags that the company is producing. That " with 500 grams" is the weight of each bag, not the total number of bags that the company is producing.

What we are considering is the NUMBER OF LOLLIES/CANDIES that are put in each bag to get that " with 500 grams".

We do that by taking a sample of 120 bags ($n=120$)and we don't know the total number of bags being produced, that is, the population size $N$.

Re: Question on Exercise 8.6

lisawaty 15 Apr 2009 13:21

Hi,

^^ thank you ser,
haha
after i read it again
thats right it is only the weight
but not the N ^^
thank you Ser !
If i have another problem, i will post it.

My regards
lisa

Re: Question on Exercise 8.6

Vinh Tran 15 Apr 2009 13:28

Hi Lisa,

Yep. If you have any different question, just create a new thread. Thanks.