1. AGENDA:
DG min
Section 9.2
Register for Mock Exam

2. Advanced Placement Statistics Section 9.2: Sample Proportions
EQ: How are sample proportions used to estimate population proportions?

3. RECALL: What are the statistical notations for proportions?
Can we really ever know the parameters about a populations?
In statistics, we use ESTIMATORS to make decisions about populations.
RECALL: What are the statistical notations for proportions?

4. New Facts:
right
left

5. also called Standard Error
See Formula Sheet!!
also called Standard Error
Independence --- Standard Error can be used when n is large enough.

6. also called Standard Error
Standard Error can be used when n is large enough.

7. Now we can use z-scores!!!

9. You will need notebook paper for these examples.
I would suggest turning your desk so you can work in a SMALL group as we go over these problems. We will work many example problems for the remainder of the course and it will “ take a village” to complete these tasks.
In Class Assignment:
p. 588 #19 , 20 , 21
You will need notebook paper for these examples.

10. #19
a) p = true proportion of all US adults who say they drink the milk from their cereal bowl.
population > 10(sample)
population > 10(1012)
population > 10,120
Population large enough for independence.
np > nq > 10
(1012)(.7) > (1012)(.3) > 10
708.4 > > 10
Normal Approximation appropriate.

11. Since only 1.86% of the samples of size n = 1012 will have 67% or fewer adults saying they drink the milk from their cereal bowl, I would consider these results unusual.

12. You will need a sample size of 4048 adults to half the standard error.
f) If the pollsters had surveyed 1012 teenagers instead of adults , the proportion who say they drink the milk in their cereal bowls would probably be higher. Teenagers are more likely to drink the milk in their bowl.

13. AGENDA:
Need to Finish p. 588 #20 , #21
DG minutes

14. #20
a) p = true proportion of all adults who attended church last week
population > 10(sample)
all adults > 10(1785)
all adults > 17,850
Population large enough for independence. (SE)
np > nq > 10
(1785)(.4) > (1785)(.6) > 10
714 > > 10
Normal Approximation appropriate.

16. #21
Problem: What is the probability that a SRS of size n = 300, is within ± .03 of the true population parameter, p = 0.4?
population > 10(sample)
all adults > 10(300)
all adults > 3,000
Population large enough for independence.(SE)
np > nq > 10
(300)(.4) > (300)(.6) > 10
120 > > 10
Normal Approximation appropriate.

17. #21
Problem: What is the probability that a SRS of size n = 1200 is within ± .03 of the true population parameter, p = 0.4?
population > 10(sample)
all adults > 10(1200)
all adults > 120,000
Population large enough for independence.
np > nq > 10
(1200)(.4) > 10 (1200)(.6) > 10
480 > > 10
Normal Approximation appropriate.

18. The probability that an SRS of adults of size n = 1200 has 37% to 43% who say they attend church regularly is 96.68%.

19. #21
Problem: What is the probability that a SRS of size n = 4800 is within ± .03 of the true population parameter, p = 0.4?
population > 10(sample)
all adults > 10(4800)
all adults > 480,000
Population large enough for independence.
np > nq > 10
(4800)(.4) > 10 (4800)(.6) > 10
1920 > > 10
Normal Approximation appropriate.

20. The probability that an SRS of adults of size n = 4800 has 37% to 43% who say they attend church regularly is 99.99%.

21. Assignment
p – 591 #25, 26, 27 (a, b), 28 – 30