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Chapter 6 Review Due 3/26

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Last updated almost 2 years ago
16 questions
Note from the author:
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4
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This review is optional but will give excellent practice for the test.
This review is optional but will give excellent practice for the test.
Question 1
1.

A study of voting chose 663 registered voters at random shortly after an election. Of these, 72% said they had voted in the election. Election records show that only 56% of registered voters voted in the election.
Match up the following statements about these percentages?

Draggable itemarrow_right_altCorresponding Item
56%
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Parameter
All voters
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Statistic
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Question 2
2.

Question 3
3.

Question 4
4.

Question 5
5.
At a high school, 85% of students are right-handed.
Let X = the number of students who are right-handed in a random sample of 10 students from the school.
What is the sample size? n= _______
What is the mean of the sampling distribution? _______ enter as a proportion, not a percent.
What is the standard deviation of the sampling distribution? _______ Round to three places past the decimal point.
Question 6
6.

Using the information in the previous problem, what is the Normal Model?
Use the notation N(

Question 7
7.

Question 8
8.

Scores on the mathematics part of the SAT exam in a recent year followed a normal distribution with mean 515 and standard deviation 114.
You choose an SRS of 100 students and calculate mean SAT Math score.
Match up the following for this situation.

Draggable itemarrow_right_altCorresponding Item
515
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sample size (n)
11.4
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Question 9
9.
In a congressional district, 52% of the registered voters are Democrats. An SRS of 100 voters is going to be polled.
What is the mean of the sampling distribution of the sample proportion of democrat voters? _______

What is the standard deviation of the sampling distribution of the sample proportion of democrat voters? _______ Round to two places past the decimal.

What is the probability of getting less than 50% Democrats in a random sample of size 100?
_______
.Keep your answer as the decimal proportion, keep all decimal places (there will be four)>
Question 10
10.

Use the information in the previous question.
What is the probability of getting a sample of 100 registered voters with more than 65% democrats?
Keep all decimals.

Question 11
11.

Question 12
12.
The amount that households pay service providers for access to the Internet varies quite a bit, but the mean monthly fee is $48 and the standard deviation is $20.
The distribution is not normal: Many households pay a base rate for low-speed access, but some pay much more for faster connections so the distribution is strongly right skewed.

A sample survey asks an SRS of 500 households with Internet access how much they pay per month. Let X-bar be the mean amount paid by the members of the sample.

Calculate the mean and standard deviation of the sampling distribution of the sample means.
Sampling distribution sample mean = _______
Sampling distribution of sample means standard deviation = _______
Round to three places past the decimal.
Question 13
13.

Question 14
14.
Use the information in the previous two questions:
In a sampling distribution, find the probability that the average amount paid by the sample of households exceeds $50.

z-score = _______ round to two places past the decimal

Probability = _______ Keep the probability as a decimal proportion
Question 15
15.
Use the information from the previous 3 questions:
In a sampling distribution, what is the probability that the average amount paid by the sample of households is less than $46.50.
z-score = _______ round to two places past the decimal

Probability = _______ Keep your answer as a decimal proportion.
Question 16
16.

Draggable itemarrow_right_altCorresponding Item
arrow_right_alt
arrow_right_alt
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arrow_right_alt
arrow_right_alt
arrow_right_alt
arrow_right_alt
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72%
Sample
663 regsitered voters
Population
Vermont is particularly beautiful in early October when the leaves begin to change color. At that time of year, a large proportion of cars on Interstate 91 near Brattleboro have out-of-state license plates.
Suppose a Vermont state trooper randomly selects 50 cars driving past Exit 2 on I-91, records the state identified on the license plate, and calculates the proportion of cars with out-of-state plates.
What is the Vermont state trouper recording?
Which of the following describes the sampling distribution of the sample proportion in this context?
He is recording the proportion of cars with license plates in the sample of 50 cars passing this exit.
He is recording the proportion of cars without a license plate in the sample of 50 cars passing this exit.
He is recording the proportion of cars with out of state license plates in the sample of 50 cars passing this exit.
The distribution of the proportion of cars with out-of-state plates in all possible samples of 50 cars passing this exit
He is recording the proportion of cars with instate license plates in the sample of 50 cars passing this exit.
The distribution of state for all cars passing this exit
The distribution of state for all cars in the trooper’s sample of cars passing this exit
The distribution of the proportion of cars with out-of-state plates in the trooper’s sample of 50 cars passing this exit
A polling organization wants to estimate the proportion of voters who favor a new law banning smoking in public buildings.
The organization decides to increase the size of its random sample of voters from about 1500 people to about 4000 people right before an election.
The effect of this is to
and reduce the bias of the estimate.
and increase the bias of the estimate.
and reduce the variability of the estimate.
and increase the variability of the estimate.
increase the precision
decrease the precision
The central limit theorem is important in statistics because it allows us to use the normal distribution to find probabilities involving the sample mean if the
sample size is reasonably large for any population shape.
sample size is reasonably large.
population size is reasonably large for any population shape.
population size is reasonably large.
The population distribution is normal OR
The population distribution is normal AND
The student newspaper at a large university asks an SRS of 250 undergraduates, “Do you favor eliminating the carnival from the end-of-term celebration?”
In the sample, 150 of the 250 undergraduates are in favor.
Suppose that 55% of all undergraduates favor eliminating the carnival. If you took a very large number of SRSs of size n = 250 from this population, the sampling distribution of the sample proportion p-hat would have which of the following characteristics?
skewed right
skewed left
Mean 0.55,
Mean 0.60,
standard deviation 0.03,
standard deviation unknown,
shape unknown,
approximately normal,
standard deviation 0.04,
114
100
Using the information above, suppose an actual sample of 100 of the registered voters actually resulted in 65% democrats. Would you have convincing evidence that the estimated 52% democrat voters was incorrect? Explain.
the results give convincing evidence that the actual percentage is more than 52%
the probability of getting 65% democrats is greater than 5%
No
the results give convincing evidence that the percentage has not changed and remains 52%.
the results are not unusual
the probability of getting 65% democrats is less than 5%
the results are very unusual
Yes
Use the information from the previous question:
What is the shape of the population and the sampling distribution of x-bar ? Justify.
the sampling distribution of sample means will be roughly normal
due to the sample sizes greater than or equal to 30.
due to the sample size less than 30.
The population is strongly right skewed but
The population is roughly normal so
the sampling distribution of sample means will also be right skewed
Match the correct notation with the definition.
Population Mean
Population Proportion
Mean of the Sampling Distribution of Means
Mean of the Sampling Distribution of Proportions
p-hat
Sample Mean
X-bar
Sample proportion
Standard Deviation of the Sampling Distribution of means
Standard Deviation of the Sampling Distribution of proportions