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UNIT 5 — MILESTONE 5
Score 23/24
You passed this Milestone
23 questions were answered correctly.
1 question was answered incorrectly.
1
A coin is tossed 50 times, and the number of times heads comes up is counted.
Which of the following statements about the distributions of counts and proportions is FALSE?
The distribution of the count of getting heads can be approximated with a normal distribution.
The count of getting heads is a binomial distribution.
The count of getting heads from a sample proportion of size 20 can be approximated with a normal
distribution.
The distribution of the count of getting tails can be approximated with a normal distribution.
RATIONALE
If we look at the counts from a large population of success and failures (2 outcomes), this is called a binomial
distribution, not a normal distribution.
CONCEPT
Distribution of Sample Proportions
2
Edwin conducted a survey to find the percentage of people in an area who smoked regularly. He defined the label
“smoking regularly” for males smoking 30 or more cigarettes in a day and for females smoking 20 or more. Out of
635 persons who took part in the survey, 71 are labeled as people who smoke regularly.
What is the standard error for the sample proportion? Answer choices are rounded to the thousandths
place.
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0.112
2.818
2.778
0.013
RATIONALE
We can note the SE of the proportion is
square root of fraction numerator p with hat on top q with hat on top over denominator n end fraction end root.
If we note that , which means .
So if we take all this information we can note SE = .
CONCEPT
Calculating Standard Error of a Sample Proportion
3
What do the symbols , , and represent?
Population parameters
Variables of interest
Sample statistics
Defined variables
RATIONALE
Recall that p
is the population proportion, sigma is the population standard deviation, and mu is the
population mean. Since all these values come from the population, they are parameters.
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CONCEPT
Sample Statistics and Population Parameters
4
Edwin conducted a survey to find the percentage of people in an area who smoked regularly. He defined the label
“smoking regularly” for males smoking 30 or more cigarettes in a day and for females smoking 20 or more. Out of
635 people who took part in the survey, 71 are labeled as people who smoke regularly.
Edwin wishes to construct a significance test for his data. He finds that the proportion of chain smokers nationally
is 14.1%.
What is the z-statistic for this data? Answer choices are rounded to the hundredths place.
-0.24
-0.03
-2.34
-2.11
RATIONALE
To make things a little easier, let's first note the denominator
We can now note that
Finally, subbing all in we find
*note that if you round, the values can be slightly different.
CONCEPT
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