1. 2.) A. Incorrect, the prob. Is either 0 or 1, but we don’t know which.
Incorrect; x-bar is always in the center of the confidence interval
**Incorrect; the different samples will yield different sample means, and the distribution of those sample means is used to provide an interval that captures the population mean
Incorrect; there is nothing magical about the interval from this one sample. Our method for computing confidence intervals is based on capturing the mean of the population, not a particular interval from one sample.
Correct
3.)No, This is a statement about the mean score for all young men, not about individual scores.

2. 4.) A. Normal with a mean of μ and standard deviation of 0.0566.B.
m=0.1132
About 95% of them
Your answers will vary µ µ µ µ µ µ

3. 5.) A. 48% to 54%
51% is only from one sample; not every sample will give us the same results.
95% confidence means that this interval was found using a procedure that produces correct results 95% of the time.
Undercoverage or nonresponse

4. Confidence Intervals when σ is known
Section 10.1

5. You need 3 conditions: 1.) SRS
2.) Normality (original distribution is Normal or by the CLT, n>30)
3.) Independence: Observations are independent OR population is 10 times the sample

6. Confidence Interval when σ is known:
Margin of error

7. -z* z*
Area=
Area=C
Confidence Level (C)
Critical values (z*)
90%
95%
99%

8. Inference Toolbox
1.) Identify the population and the parameter you want to draw a conclusion about (WRITE A SENTENCE!)
2.) State conditions. (SRS, Normality, Independence)
3.) Do the calculations, including the formula you are using.
4.) Interpretation IN CONTEXT of the problem. (WRITE A SENTENCE!)
We are ____% confident that…

9. Pg. 632 #9 in Class

10. Margin of Error Gets smaller when:
z* is smaller (but confidence level goes down)
σ is smaller (but you can’t control)
n is larger

11. Margin of Error…
Only covers random sampling error; it DOES NOT cover incorrect/bad data collection Sample size for Desired Margin of Error:

12. In class: pg. 637 #14

13. Cautions: pg. 636
“GIGO”=garbage in, garbage out

14. Pg. 632 #10,11 Pg. 637 #15
Homework