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Unformatted text preview: needed to be 99% conﬁdent Sampling Distribution of the Sample Proportion (continued Checkpoint 3  Modeling and Inference
Sampling Distribution of the Sample Proportion Example 5. Find the sample size needed to estimate the proportion
of believers within 3% with a conﬁdence level of 98%.
6. Suppose we want to cut the margin of error to 1%.
What is the necessary sample size? Sampling Distribution of the Sample Proportion (continued Checkpoint 3  Modeling and Inference
Sampling Distribution of the Sample Proportion Example 2 (for Sample Proportion)
Suppose of all voters in the U.S., 40% are in favor of
Candidate Y for president. Gallup poll takes a sample of 2400
people.
1
What proportion of sample would be expected to vote for
Candidate Y?
2 What does CLT for the proportion tell us about the mean
and SD for the proportion of people who vote for Cand
Y? Use
p (1 − p )
ˆ
p ∼ Normal p ,
n Sampling Distribution of the Sample Proportion (continued Checkpoint 3  Modeling and Inference
Sampling Dis...
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This note was uploaded on 03/12/2014 for the course STATS 10 taught by Professor Ioudina during the Spring '08 term at UCLA.
 Spring '08
 Ioudina

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