Mathematical Statistics with Applications
7th Edition
ISBN: 9781133384380
Author: Dennis Wackerly; William Mendenhall; Richard L. Scheaffer
Publisher: Cengage Learning US
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Textbook Question
Chapter 12.2, Problem 4E
Refer to Exercise 12.3. How many observations are needed for a 95% confidence interval to be 2 units in length if n1 = n2?
12.3 Suppose, as in Exercise 12.1, that two populations have respective variances
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Students have asked these similar questions
(a) Test the hypothesis.
Consider the hypothesis test Ho
=
:
against H₁o < 02. Suppose that the sample sizes aren₁ =
7 and n₂
= 13 and that
$²
= 22.4 and $22
= 28.2. Use α = 0.05.
Ho
is not
✓ rejected.
9-9
IV
(b) Find a 95% confidence interval on of 102. Round your answer to two decimal places (e.g. 98.76).
Let us suppose we have some article reported on a study of potential sources of injury to equine veterinarians conducted at a
university veterinary hospital. Forces on the hand were measured for several common activities that veterinarians engage in when
examining or treating horses. We will consider the forces on the hands for two tasks, lifting and using ultrasound. Assume that both
sample sizes are 6, the sample mean force for lifting was 6.2 pounds with standard deviation 1.5 pounds, and the sample mean force
for using ultrasound was 6.4 pounds with standard deviation 0.3 pounds. Assume that the standard deviations are known.
Suppose that you wanted to detect a true difference in mean force of 0.25 pounds on the hands for these two activities. Under the null
hypothesis, 40 = 0. What level of type II error would you recommend here?
Round your answer to four decimal places (e.g. 98.7654). Use a
= 0.05.
β
= i
What sample size would be required?
Assume the sample sizes are to be equal.…
=
Consider the hypothesis test Ho: μ₁ = μ₂ against H₁ μ₁ μ2. Suppose that sample sizes are n₁ =
15 and n₂ =
15, that x1 = 4.7
and X2 = 7.8 and that s² = 4 and s² = 6.26. Assume that o and that the data are drawn from normal distributions. Use
απ 0.05.
(a) Test the hypothesis and find the P-value.
(b) What is the power of the test in part (a) for a true difference in means of 3?
(c) Assuming equal sample sizes, what sample size should be used to obtain ẞ = 0.05 if the true difference in means is - 2? Assume
that α = 0.05.
(a) The null hypothesis is
98.7654).
rejected. The P-value is 0.0008
(b) The power is 0.94
. Round your answer to four decimal places (e.g.
Round your answer to two decimal places (e.g. 98.76).
(c) n₁ = n2 =
1
. Round your answer to the nearest integer.
Chapter 12 Solutions
Mathematical Statistics with Applications
Ch. 12.2 - Suppose that you wish to compare the means for two...Ch. 12.2 - Refer to Exercise 12.1. Suppose that you allocate...Ch. 12.2 - Suppose, as in Exercise 12.1, that two populations...Ch. 12.2 - Refer to Exercise 12.3. How many observations are...Ch. 12.2 - Suppose that we wish to study the effect of the...Ch. 12.2 - Refer to Exercise 12.5. Consider two methods for...Ch. 12.2 - Refer to Exercise 12.5. Why might it be advisable...Ch. 12.2 - The standard error of the estimator 1 in a simple...Ch. 12.3 - Consider the data analyzed in Examples 12.2 and...Ch. 12.3 - Two computers often are compared by running a...
Ch. 12.3 - When Y1i, for i = 1, 2,, n, and Y2i, for i = 1,...Ch. 12.3 - Prob. 12ECh. 12.3 - Prob. 13ECh. 12.3 - Prob. 14ECh. 12.3 - A plant manager, in deciding whether to purchase a...Ch. 12.3 - Muck is the rich, highly organic type of soil that...Ch. 12.3 - Prob. 17ECh. 12.4 - Prob. 18ECh. 12.4 - Prob. 19ECh. 12.4 - Prob. 20ECh. 12.4 - Prob. 21ECh. 12.4 - Prob. 22ECh. 12.4 - Prob. 23ECh. 12.4 - Prob. 24ECh. 12.4 - Prob. 25ECh. 12.4 - Prob. 26ECh. 12.4 - Complete the assignment of treatments for the...Ch. 12 - Prob. 28SECh. 12 - Prob. 29SECh. 12 - Prob. 30SECh. 12 - Prob. 31SECh. 12 - Prob. 32SECh. 12 - Prob. 33SECh. 12 - Prob. 34SECh. 12 - The earths temperature affects seed germination,...Ch. 12 - An experiment was conducted to compare mean...Ch. 12 - Prob. 37SE
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