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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

Hi Prof i was wondering if you could help me with number 38 from chapter nine in the homework.

I keep trying and trying and i keep getting the wrong answer and i don't know what I'm doing.
I have

Men
N: 60
p hat: i divided 52/60: .8667
and q hat is 1-.8667 and i got .133

Women
N: 58
p hat: 56/58 and got .9655
q hat: 1-.9655

i don't know if thats the right data but i keep getting the wrong answer

Posted to STATS 2 on Monday, October 13, 2014   Replies: 1


Professor Mcguckian
10/13/2014
9:54 PM EST

Hi Sandra,

Here is what you need to do for this problem:

The data you listed is correct.

The confidence level is 90%, so the alpha is 10%. This means Za/2 = Z0.05 = 1.645.

Then the margin of error is then, E = 1.645*SqrRoot(0.8667*0.1333/60 + 0.9655*0.0345/58) = 0.0822

Finally, (pm - pw - E, pm - pw + E) = (-0.0988 - 0.0822, -0.0988 + 0.0822) = -0.181 to -0.017. 

*If you round to whole percents, -18% to -2%.

Hope that helps you find your error,

Professor McGuckian

 

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