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ASK THE PROFESSOR FORUM

Course Documents

Chapter 1 - Intro

Chapter 2 - Methods for Describing Sets of Data

Chapter 3 - Probability

Chapter 4 - Discrete Random Variables

Chapter 5 - Normal Random Variables

Chapter 6 - Sampling Distributions

Chapter 7 - Confidence Intervals

Chapter 8 - Tests of Hypothesis: One Sample

Chapter 9 - Confidence Intervals and Hypothesis Tests: Two Samples

Sample Exam I: Chapters 1 & 2

Sample Exam II: Chapters 3 & 4

Sample Exam III: Chapters 5 & 6

Sample Exam IV: Chapters 7 & 8

Ask the Professor Forum

Hello Professor,

I am trying to do Homework Problem 40 for Section 7.4. I can't seem to figure out how to use it with Z instead of T. Can you please explain how to do this problem?

Thank you

Posted to STATS 2 on Tuesday, September 10, 2013   Replies: 2


Professor Mcguckian
09/10/2013
11:30 PM EST

Hi Genessys,

Here is a video explaining the problem:

 


Professor Mcguckian
09/11/2013
12:46 AM EST

Just to summarize what the video shows: the first step here is to check if n is greater than 30.  If it is, we find Za/2 not ta/2. Since, we are finding Za/2, we do not need to worry about the degrees of freedom.  We go to the t-table looking up a/2 in the top row, then we go straight to the bottom of that 0.01 row where the Za/2 value is located. 

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