Transcript More things to consider…

Review
Unit 7: Hypothesis Testing
Things to consider:
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What is the p-value?
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What is more serious – Type I error or Type
II?
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How do we choose the level of significance?
What does it represent?
More things to consider…
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What is a hypothesis?
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When do I reject the alternative hypothesis?
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What’s the difference between t and z?
Know:
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How to write hypotheses
What a type I/II error is and the
consequences.
How to choose the level of significance.
What’s the probability of type I/II error called?
Be able to run a large sample proportion ztest, 1 sample mean z- test, and a 1 sample
mean t-test.
Harley-Davidson motorcycles make up 14% of all the motorcycles
registered in the United States. You plan to interview an SRS of 500
motorcycle owners. What’s the probability that 20% or more own
Harleys?
A study found that 48 out of the 200 students surveyed had cheated on
a test. Calculate a 90% confidence interval for the true proportion of
student who have cheated on a test.
Approximately 82% of all students have copied a
classmate’s homework. I have a class of 32.
• How many do you expect to find have copied?
• What is the probability that exactly 28 have copied?
• What is the probability that at least 25 have copied?
• What is the probability that less than 21 have copied?
The number of flaws per square yard in a type of carpet material varies
with a mean of 1.8 flaws per square yard and st. dev. 1.2 flaws. An
inspector studies 200 square yards, what the probability that the mean
number of flaws exceeds 2 per square yard?
The probability that Ed hits the ball when he goes
to bat is 0.23. Find the probability that he doesn’t
get a hit until his 3rd time at bat.
If I want to estimate the mean SAT score within 5 points with a 99%
confidence, how large of a sample would you need. The standard
deviation is 100.
The composition of the earth’s atmosphere may have changed over
time. The gas in bubbles within amber should be a sample of the
atmosphere at the time the amber was formed. The measures on
specimens of amber are shown below. Construct and interpret a 95%
confidence interval for the mean percent of nitrogen in ancient air.
63.4
65
64.4
63.3
54.8
64.5
60.8
Find the mean and standard deviation of the
following:
x
p(x)
20
0.02
25
0.03
30
0.08
35
0.12
40
0.22
45
50
0.28
I want to test my sweet pea seeds to determine the
germination rate, that is the percent of seeds that sprout.
How large of a sample of seeds will I need to be within 4% of
the true proportion?
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