Statistics problem

[misle]

Okay, there is a concept that I'm not getting and I have a quiz over it in an hour.

We are using Intro to Probability and Statistics by Milton.

In the book, it says the confidence interval on p is:
*note: p' = p hat -> I'm using ' for ease.

p' +/- Z(alpha/2) * Sqrt(p'(1-p')/n)

Z is standard normal
p' = number in sample with trait / sample size

Alpha is 5% or 0.05

My problem is: how do I find Z(0.025)?
I have the Standard normal table (-3.41 - 3.41 in increments of .1), but I guess I don't know how to apply it to this problem.

 

[MartyMcFly3]

can you give me the entire problem you are having difficulty with? If i saw the whole thing i might be able to help.

 

[misle]

I think I might have figured it out.

The Z(alpha/2) is what was throwing me. I think I find the Z value that corresponds with 1-0.025 = .975 => Z = 1.96

 

[MartyMcFly3]

yeah, 1.96 is the standard 95% Confidence Interval.

 

[misle]

Thanks. It always seems like when I finally ask for some help, I figure it out. Kinda annoying, you know.

Thanks again McFly

 

[MartyMcFly3]

LOL yeah happens to me too. No problem and good luck with the quiz.