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statistics own me.

A

alphatarget1

Diamond Member
wow, i don't know what I'm doing wrong, this sucks.

the proportion of adults living in a small town who are college graduates is estimated to be p = 0.6. to tes this hypothesis, a random sample of 200 adults is selected. the acceptance region is defined to be 110<x<130 where x is the number of college raudates in our sample. use the normal approximation.

evalute alpha (probability of a type I error).

well ok, i figured out the x bar (mean) to be =np which is (200*0.6) = 120 and my sigma to be (200*0.6*0.4)^(1/2) = 6.92 something. did a normal cumulative distribution from a really small number to 110, with the mean = 120 and st.dev = 6.92. i didn't get what the book got, must've done something wrong. any ideas?
 
First year stats it looks like. If this thread is around tomorrow I'll help.... too sleepy from Calculus tho.
 
So is this hypothesis testing or do they just want to know the confidence interval?

So I get Z = 1.4434 and I forget what that makes alpha... something like 14.88%
 
Originally posted by: RGUN
So is this hypothesis testing or do they just want to know the confidence interval?

So I get Z = 1.4434 and I forget what that makes alpha... something like 14.88%
Click to expand...

hypothesis testing, but if i find the right Z value i should get the right answer.

i got the same Z too
 
If this is a hypothesis testing problem then dont you have two unknowns the way you word the question? 1 being whether or not the hypothesis is true and 2 being the testing interval?

When the test interval is ambiguous we have always been told to use alpha = 0.05, also, have you considered how being a one tailed or two tailed test might affect your values?
 
Originally posted by: RGUN
If this is a hypothesis testing problem then dont you have two unknowns the way you word the question? 1 being whether or not the hypothesis is true and 2 being the testing interval?

When the test interval is ambiguous we have always been told to use alpha = 0.05, also, have you considered how being a one tailed or two tailed test might affect your values?
Click to expand...


we're trying to determine alpha...
 
oh ya, you check if the p-value > or less then alpha... or maybe not..

anyways i would help, but I sold my book already.
 
Speaking of getting owned by statistics... I kid you not this was a question from my statistics exam last week:

***** University orders 12 power supplies, 4 power supplies are defective, what are the chances of 2 or more defective power supplies in the sample.

That was it... there was nothing else, I told the prof 4 times we didnt have enough information to solve the problem but she kept saying I wasnt reading the question properly..... she doesnt speak english that well... and she writes like she speaks.
 
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