1. AP/H Statistics
Mrs. LeBlanc – Perrone Name: ______________________________
8.3: Critical RegionGuided Notes Date: ___________
8.3 Testing a Proportion Using Critical Regions
Testing a Proportion Using Critical Regions
o To test a proportion using critical regions, we will use a similar process to those for testing the
mean (8.1 & 8.2)
o The main difference is that we are working with a _____________________________________
o When using the critical region method, we check if the sample test statistic falls in the critical
region.
 If it _________, we ___________
 If it _______________, then we ________________
 Recall that when using critical regions, the ________________________ of the sketch is
 Since the distribution is _______________________________________ we find the
critical values using invNorm
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2. AP/H Statistics
Mrs. LeBlanc – Perrone
How to Test
1. ________________________________________________________________________
Is this a binomial experiment with trials?
Does represent the probability of success?
Identify
Is the sample large? (Is and ?) (Use p from )
If yes, then the distribution can be approximated by the normal distribution
2. ________________________________________________________________________
________________________________________________________________________
3. ________________________________________________________________________
Test Statistic:
4. ________________________________________________________________________
The area of the critical region =
5. Conclude the test
__________________________________________________________________
__________________________________________________________________
6. Interpret the results in the context of the application
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3. AP/H Statistics
Mrs. LeBlanc – Perrone
EXAMPLE: Testing , Critical Regions
A botanist has produced a new variety of hybrid wheat that is better able to withstand drought than
other varieties. The botanist knows that for the parent plants, the proportion of seeds germinating is
80%. The proportion of seeds germinating for the hybrid variety is unknown, but the botanist claims
that it is 80%. To test this claim, 400 seeds from the hybrid plant are tested, and it is found that 312
germinate. Use a 5% level of significance to test the claim that the proportion germinating for the
hybrid is 80%.
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4. AP/H Statistics
Mrs. LeBlanc – Perrone
Summary Questions
1. How is testing (using critical values) similar to testing (using critical values)?
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2. When testing using critical values, what is the test statistic for?
____________________________________________________________________________________
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“HOT” Question:
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