1. Warm-up 9.3 and 9.4 C.I and Inference Test of Two Means
1. A doctor wishes to compare the resting heart rates of his younger patients (younger than 30 years old) versus his older patients. Which of the following graphical displays is inappropriate. A. Back-to-back stemplot B. Parallel boxplots C. Side by side histograms D. Scatterplots E. All of the above are appropriate. 2. Consider n pairs of numbers. Suppose Of the following which could be the least squares line? A. y = 2 + x B. y = x C. y = x D. y = 5/3 – x E. y = 6 - x

2. H.W. Answers to 8.4 D# 45
S.E. for n = 10 is 0.071
S.E. for n = 50 is 0.158

3. 9.3 C.I. and Significance Test for Two Means
Comparing means is not that different from comparing two proportions.
Remember with means t* is used instead of z*
To find t* use the table NOT InvNorm.
Confidence Interval
t* for degrees of freedom (degrees of freedom is not easy to find)

4. Finding the Confidence Interval for a difference of 2 Means
Judging from the boxplot, the generic batteries seem to have lasted about 20 minutes longer than the brand-name batteries. Before we change our buying habits, what should we expect to happen with the next batteries we buy? 6 sets of AA batteries were randomized and tested for duration length. Calculate the 95% C.I. to find the true difference between the two means.

5. Significance Test Difference Between Two Means
It is a common believe that women tend to live longer than men. Random samples from death records for mean and women in Montgomery County were taken, and age at the time was recorded. The average age of the 48 males was with a standard deviation of years, while the average age of the 40 females was 78.7 years with a standard deviation of years. Do women in this county tend to live longer than men? Give the appropriate statistical evidence. STAT => TESTS=>2-SampTTest Ho: HA:

6. Direction for the rest of the block
Finish the notes, both the confidence interval AND the significance test.
When you finish organize your notes and show them to me.
10.1, 10.2, 10.3, Ch.11 Day 1, Ch. 11 Day 2, 8.3 & 8.4, 9.3 & 9.4 (7 notes with warm-ups 14 pts each 7 x 14 = 98)
*****Don’t bring me any notes that are not fillled in *****
Once you show me your notes start on the multiple choice for the practice cumulative tests.
Remember to return formula sheets AND the cumulative practice test if you borrowed the class set!
REMEMBER the cumulative test will be timed!
2minutes per multiple choice (2* 12 = 24minutes!)
15 minutes per free response ( 15* 3 = 45 minutes!) = 70

7. Significance Test for Two Means
t is about 3.28; p-value is I reject the null hypothesis that there is no difference between the two means. If there was no difference there is only 8 out of 10,000 samples that would have the same mean difference or more extreme. Women in Montgomery County tend to live longer than men. Complete the multiple choice for h.w. We will review the answers, next block. You will be given time to complete the free-response.