STAT 200 Week 5 Homework Solution Correct Answers
Week 5 homework answers for a statistics course.
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STAT 200 Week 5 Homework Solution Correct Answers
Lane Chap. 10
10. The effectiveness of a blood-pressure drug is being investigated. How might an
experimenter demonstrate that, on average, the reduction in systolic blood pressure is 20 or
more?
12. A person claims to be able to predict the outcome of flipping a coin. This person is
correct 16/25 times. Compute the 95% confidence interval on the proportion of times this
person can predict coin flips correctly. What conclusion can you draw about this test of his
ability to predict the future?
15. You take a sample of 22 from a population of test scores, and the mean of your sample
is 60.
(a) You know the standard deviation of the population is 10. What is the 99% confidence
interval on the population mean.
(b) Now assume that you do not know the population standard deviation, but the standard
deviation in your sample is 10. What is the 99% confidence interval on the mean now?
18. You were interested in how long the average psychology major at your college studies
per night, so you asked 10 psychology majors to tell you the amount they study. They told
you the following times: 2, 1.5, 3, 2, 3.5, 1, 0.5, 3, 2, 4.
(a) Find the 95% confidence interval on the population mean. (b) Find the 90% confidence
interval on the population mean.
Illowsky Chap. 8
Lane Chap. 10
10. The effectiveness of a blood-pressure drug is being investigated. How might an
experimenter demonstrate that, on average, the reduction in systolic blood pressure is 20 or
more?
12. A person claims to be able to predict the outcome of flipping a coin. This person is
correct 16/25 times. Compute the 95% confidence interval on the proportion of times this
person can predict coin flips correctly. What conclusion can you draw about this test of his
ability to predict the future?
15. You take a sample of 22 from a population of test scores, and the mean of your sample
is 60.
(a) You know the standard deviation of the population is 10. What is the 99% confidence
interval on the population mean.
(b) Now assume that you do not know the population standard deviation, but the standard
deviation in your sample is 10. What is the 99% confidence interval on the mean now?
18. You were interested in how long the average psychology major at your college studies
per night, so you asked 10 psychology majors to tell you the amount they study. They told
you the following times: 2, 1.5, 3, 2, 3.5, 1, 0.5, 3, 2, 4.
(a) Find the 95% confidence interval on the population mean. (b) Find the 90% confidence
interval on the population mean.
Illowsky Chap. 8
100. What is meant by the term “90% confident” when constructing a confidence interval for
a mean?
a. If we took repeated samples, approximately 90% of the samples would produce the same
confidence interval.
b. If we took repeated samples, approximately 90% of the confidence intervals calculated
from those samples would contain the sample mean.
c. If we took repeated samples, approximately 90% of the confidence intervals calculated
from those samples would contain the true value of the population mean.
d. If we took repeated samples, the sample mean would equal the population mean in
approximately 90% of the samples.
106. Suppose that a committee is studying whether or not there is waste of time in our
judicial system. It is interested in the mean amount of time individuals waste at the
courthouse waiting to be called for jury duty. The committee randomly surveyed 81 people
who recently served as jurors. The sample mean wait time was eight hours with a sample
standard deviation of four hours.
a.
i. x ¯ = __________
ii. sx = __________
iii. n= __________
iv. n– 1 = __________
b. Define the random variables X and X ¯ in words.
c. Which distribution should you use for this problem? Explain your choice.
d. Construct a 95% confidence interval for the population mean time wasted.
a mean?
a. If we took repeated samples, approximately 90% of the samples would produce the same
confidence interval.
b. If we took repeated samples, approximately 90% of the confidence intervals calculated
from those samples would contain the sample mean.
c. If we took repeated samples, approximately 90% of the confidence intervals calculated
from those samples would contain the true value of the population mean.
d. If we took repeated samples, the sample mean would equal the population mean in
approximately 90% of the samples.
106. Suppose that a committee is studying whether or not there is waste of time in our
judicial system. It is interested in the mean amount of time individuals waste at the
courthouse waiting to be called for jury duty. The committee randomly surveyed 81 people
who recently served as jurors. The sample mean wait time was eight hours with a sample
standard deviation of four hours.
a.
i. x ¯ = __________
ii. sx = __________
iii. n= __________
iv. n– 1 = __________
b. Define the random variables X and X ¯ in words.
c. Which distribution should you use for this problem? Explain your choice.
d. Construct a 95% confidence interval for the population mean time wasted.
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Document Details
University
University of Maryland
Subject
Statistics