1. WARM -UP
Through data compiled by the auto industry 12% of Americans are planning on buying a hybrid. A recent national poll randomly asked 500 adults whether they were more likely to buy a Hybrid on their next auto purchase.
Find the unbiased Center and Standard Deviation of the Sampling Distribution of .
2. Explain why you can assume normality here.
Would it be unlikely to find 16% of Americans planning to buy hybrids? Use the % sketch to support your answer.
Center = 12%
Std. Dev. =
np ≥ 10 AND n(1 – p) ≥ 10
500 • .12 = 60 ≥ 10 AND 500 • (1 – .12) = 440 ≥ 10 √

2. 12% of Americans are planning on buying a hybrid.
3. Sketch the Distribution to determine if 16% is unlikely.

3. SAMPLING DISTRIBUTIONS
Chapter 18
SAMPLING DISTRIBUTIONS
The Sampling Distribution of a statistic is the distribution of values taken by the statistic in all possible samples of the same size from the same population.
Center, Shape, and Spread are how we describe a sampling distribution.

4. SAMPLING DISTRIBUTIONS
What proportion of beads are blue?

5. SAMPLING DISTRIBUTIONS
Record a guess to what % of the beads are blue.
Each person will come to the front and use the scoop to obtain a random sample of beads.
Calculate what proportion of the beads are blue.
Record the % on a post-it note and stick on the number line at the appropriate location. (Stack them vertically for duplicate %’s)

6. The True Proportion of blue beads is 40%.
If the True Proportion of blue beads is 40%, what is the probability that you would have scooped a sample of more than 50% blue?...

7. THE CALCULATIONS of PROBABILITY
To calculate the probability of a proportional event:
1. Write down the statement:
or Draw the labeled curve,
2. Calculate the z-score,
3. Find the Probability using: normalcdf.

8. The true proportion of beads that are blue is 40%
The true proportion of beads that are blue is 40%. What is the probability that you would have scooped a sample of 30 beads that represented more than 50% blue beads?

9. Conditions/Assumptions:
The true proportion of beads that are blue is 40%. What is the probability that you would have scooped a sample of 30 beads that represented more than 50% blue beads?
Conditions/Assumptions:
SRS: Random event
Approximately normal:
30 • .40 = 12 ≥ 10 AND 30• (1 – .4) = 18 ≥ 10
Independence: ≥ 10 • 30 = 300

10. Through polls of polls, 41% of Americans are planning on voting Republican . A recent poll asked 800 adults whether they were more likely to vote for the Republican candidate.
1. Find the probability that over 51% of adults will vote for the republican candidate.

11. HW PAGE 428: 9,10,13,15,16

13. Conditions/Assumptions:
SRS: Stated
Approximately normal:
n • p ≥ 10 AND n • (1 – p) ≥ 10
Independence: Population ≥ 10 • n

14. Through data compiled by the auto industry 12% of Americans are planning on buying a hybrid. A recent national poll asked 500 adults whether they were more likely to buy a Hybrid on their next auto purchase.
1. Find the probability that over 16% of adults will buy hybrids.

15. II. THE CALCULATIONS of PROBABILITY
SAME EXAMPLE: A national political poll asked 2150 adults whether they approved of Congress. Suppose in fact, nationally 28% of all adults said they did.
1. Find the probability that over 30% of adults approve of Congress.

16. RELATIONSHIPS AND THE DREADED BREAK UP!

17. SAME EXAMPLE: A national political poll asked 2150 adults whether
SAME EXAMPLE: A national political poll asked 2150 adults whether they approved of Congress. Suppose in fact, nationally 28% of all adults said they did.
2. Find the probability that between 25% and 29% of adults approve of Congress.

18. A statistic used to estimate a parameter is Unbiased if the statistic is equal to or approximately equal to the true value of the parameter for the population.