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MATH 225N MATHWeek 6 Math 225n Statistics Quiz
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MATH 225N MATHWeek 6 Math 225n Statistics Quiz
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Week 6 Quiz
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Question 1
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A statistics professor recently graded final exams for students in her introductory statistics course. In a review
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of her grading, she found the mean score out of 100 points was a x¯=77, with a margin of error of 10.
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Construct a confidence interval for the mean score (out of 100 points) on the final exam.
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Answer: (67, 87)
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Question 2
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A random sample of adults were asked whether they prefer reading an e-book over a printed book. The
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survey resulted in a sample proportion of p′=0.14, with a sampling standard deviation of σp′=0.02, who
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preferred reading an e-book.
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Use the empirical rule to construct a 95% confidence interval for the true proportion of adults who prefer e-
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books.
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Answer: ( 0.10, 0.18)
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Question 3
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The pages per book in a library are normally distributed with an unknown population mean. A random sample
of books is taken and results in a 95% confidence interval of (237,293) pages.
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MATH 225N MATHWeek 6 Math 225n Statistics Quiz
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What is the correct interpretation of the 95% confidence interval?
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We estimate with 95% confidence that the sample mean is between 237 and 293 pages.
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We estimate that 95% of the time a book is selected, there will be between 237 and 293 pages.
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We estimate with 95% confidence that the true population mean is between 237 and 293 pages.
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Question 4
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MATH 225N MATHWeek 6 Math 225n Statistics Quiz
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The population standard deviation for the heights of dogs, in inches, in a city is 3.7 inches. If we want to
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be 95% confident that the sample mean is within 2 inches of the true population mean, what is the
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minimum sample size that can be taken? Round up to the nearest integer.
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Answer: 14 dog heights
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Question 5
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Clarence wants to estimate the percentage of students who live more than three miles from the school. He
wants to create a 98% confidence interval which has an error bound of at most 4%. How many students
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should be polled to create the confidence interval?
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z0.10 z0.05 z0.02 z0.01 z0.005
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1.28 1.64 1.96 2.32 2.57
2 5 0 6 6
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Use the table of values above.
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Answer: 846 Students
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Question 6
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The average score of a random sample of 87 senior business majors at a university who took a certain
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standardized test follows a normal distribution with a standard deviation of 28. Use Excel to determine
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a 90% confidence interval for the mean of the population. Round your answers to two decimal places and
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use ascending order.. sh
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Score
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536
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462
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519
496
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517
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488
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HelpCopy to ClipboardDownload CSV
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That is correct!
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Answer: (509.30, 519.18)
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MATH 225N MATHWeek 6 Math 225n Statistics Quiz
sh
ne
la
tz
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MATH 225N MATHWeek 6 Math 225n Statistics Quiz
Sp
ne
la
sh
Sp
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Week 6 Quiz
la
tz
sh
Sp
ne
Question 1
la
A statistics professor recently graded final exams for students in her introductory statistics course. In a review
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of her grading, she found the mean score out of 100 points was a x¯=77, with a margin of error of 10.
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ne
Construct a confidence interval for the mean score (out of 100 points) on the final exam.
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tz
sh
Sp
That is correct!
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Answer: (67, 87)
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sh
Sp
ne
Question 2
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A random sample of adults were asked whether they prefer reading an e-book over a printed book. The
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survey resulted in a sample proportion of p′=0.14, with a sampling standard deviation of σp′=0.02, who
Sp
ne
preferred reading an e-book.
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Use the empirical rule to construct a 95% confidence interval for the true proportion of adults who prefer e-
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Sp
books.
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a
That is correct!
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sh
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Answer: ( 0.10, 0.18)
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Question 3
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The pages per book in a library are normally distributed with an unknown population mean. A random sample
of books is taken and results in a 95% confidence interval of (237,293) pages.
la
Sp
, ne
MATH 225N MATHWeek 6 Math 225n Statistics Quiz
sh
What is the correct interpretation of the 95% confidence interval?
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That is correct!
la
tz
sh
Sp
We estimate with 95% confidence that the sample mean is between 237 and 293 pages.
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We estimate that 95% of the time a book is selected, there will be between 237 and 293 pages.
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We estimate with 95% confidence that the true population mean is between 237 and 293 pages.
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Sp
ne
Question 4
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MATH 225N MATHWeek 6 Math 225n Statistics Quiz
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The population standard deviation for the heights of dogs, in inches, in a city is 3.7 inches. If we want to
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be 95% confident that the sample mean is within 2 inches of the true population mean, what is the
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minimum sample size that can be taken? Round up to the nearest integer.
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Sp
That is correct!
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Answer: 14 dog heights
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Question 5
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Clarence wants to estimate the percentage of students who live more than three miles from the school. He
wants to create a 98% confidence interval which has an error bound of at most 4%. How many students
la
tz
should be polled to create the confidence interval?
sh
Sp
z0.10 z0.05 z0.02 z0.01 z0.005
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5
la
1.28 1.64 1.96 2.32 2.57
2 5 0 6 6
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Sp
Use the table of values above.
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la
tz
That is correct!
sh
Sp
Answer: 846 Students
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Question 6
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The average score of a random sample of 87 senior business majors at a university who took a certain
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standardized test follows a normal distribution with a standard deviation of 28. Use Excel to determine
ne
a 90% confidence interval for the mean of the population. Round your answers to two decimal places and
la
tz
use ascending order.. sh
Sp
ne
Score
516
la
536
sh
462
Sp
461
ne
519
496
a
tz
517
l
sh
488
Sp
521
ne
HelpCopy to ClipboardDownload CSV
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sh
That is correct!
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Answer: (509.30, 519.18)
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