2. Practice For an SAT test  = 500  = 100
What is the probability that a sample of 65 people will have a mean SAT score below 525?

3. Step 1: Sketch out question

4. Step 2: Calculate the Standard Error
100 / 65 = 12.40

5. Step 3: Calculate the Z score
( ) / = 2.02

6. Step 4: Look up Z score in Table
Z = 2.02; Column B =.4783
.50
.4783

7. Practice
There is a probability that a sample of 65 people would have a mean SAT under 525

8. Practice
In a large corporation, the mean salary for all males with 3 to 5 years of experience was $28,000. Salaries (expressed in thousands) for a random sample of 10 women also having 3 to 5 years of experience were:
24, 27, 31, 21, 19, 26, 30, 22, 15, 36
Construct the 95% confidence interval for women and interpret what this means relative to the mean salary of males.

9. Practice
M = 25.1
SE = 1.97
t(9) = 2.262
20.64 to 29.56
20,640 to 29,560

10. Practice
Old book
New book – 8.29

12. Practice SE = 1.0 t = 2.064 T1 = 5.936 to 10.064 T2 = 3.936 to 8.064

14. Practice
On the next test I will give an A to the top 5 percent of this class.
The average test grade is with a SD of 6.98.
How many points on the test did you need to get to get an A?

15. Step 1: Sketch out question
.05

16. Step 2: Look in Table C
In column C get as close to .05 as you can and find the corresponding Z score = 1.64
.05

17. Step 3: Find the X score that goes with the Z score
Must solve for X
X =  + (z)()
68.26 = (1.64)(6.98)

18. Step 3: Find the X score that goes with the Z score
Must solve for X
X =  + (z)()
68.26 = (1.64)(6.98)
Thus, a you need a score of to get an A

19. Practice
6.22

20. Practice X = Stanford-Binet Y = WAIS b = .80 (15 / 16) = .75
Y = 25 + (.75)X
73.75 = 25 + (.75)65
It’s a bad idea to use the same cut off score for these two tests

21. Practice
6.5

22. Practice
Page 96 # 5.5
r = .51

23. Practice
Old book and 8.13
New book – 8.11 and 8.12

24. N 1 2 4 8 .5 16
.25 64
.125
As N (sample size) increases the standard error decreases!

25. NO CLASS ON FRIDAY 10/7