Assume that the helium porosity (in percentage) of coal samples taken from any particular seam is normally distributed with true standard deviation 0.78.(a) Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 17 specimens from the seam was 4.85. (Round your answers to two decimal places.)(b) Compute a 98% CI for true average porosity of another seam based on 15 specimens with a sample average porosity of 4.56. (Round your answers to two decimal places.)(c) How large a sample size is necessary if the width of the 95% interval is to be 0.34? (Round your answer up to the nearest whole number.)specimens(d) What sample size is necessary to estimate true average porosity to within 0.18 with 99% confidence? (Round your answer up to the nearest whole number.)specimensYou may need to use the appropriate table in the Appendix of Tables to answer this question.

Answered: Image /qna-images/answer/37bbf522-64c2-4427-8300-2c67dbb0731e.jpg

Answered: Assume that the helium porosity (in…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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69. The sample average unrestrained compressive strength for 45 specimens of a particular type of brick was com- puted to be 3107 psi, and the sample standard deviation was 188. The distribution of unrestrained compressive strength may be somewhat skewed. Does the data strong- ly indicate that the true average unrestrained compres- sive strength is less than the design value of 3200? Test using a = .001.
From generation to generation, the mean age when smokers first start to smoke varies. However, the standard deviation of that age remains constant at around 2.1 years. A survey of 38 smokers of this generation was done to see if the mean starting age is at least 19. The sample mean was 18.1 with a sample standard deviation of 1.3. Do the data support the claim at the 5% level? (i) Alpha (Enter an exact number as an integer, fraction, or decimal.)? =
The mean exam score for 44. male high school students are 19.9 and the population standard deviation is 5.2. The mean exam score for 55female high school students is 19.4 and the population standard deviation is 4.9. At α=0.01, can you reject the claim that male and female high school students have equal exam scores? Complete parts (a) through (e). (a) Identify the claim and state H0 and Ha. What is the claim? A. Male high school students have lower exam scores than female students. B. Male and female high school students have different exam scores. C. Male and female high school students have equal exam scores. D. Male high school students have greater exam scores than female students. What are H0 and Ha? Find the critical value(s) and identify the rejection region(s). The critical value(s) is/are Find the standardized test statistic z for μ1−μ2.
Suppose μ₁ and ₂ are true mean stopping distances at 50 mph for cars of a certain type equipped with two different types of braking systems. The data follows: m = 8, x = 115.6, $₁=5.09, n = 8, y = 129.5, and s₂ = 5.33. Calculate a 95% CI for the difference between true average stopping distances for cars equipped with system 1 and cars equipped with system 2. (Round your answers to two decimal places.) USE SALT Does the interval suggest that precise information about the value of this difference is available? O Because the interval is so narrow, it appears that precise information is available. O Because the interval is so wide, it appears that precise information is available. O Because the interval is so narrow, it appears that precise information is not available. O Because the interval is so wide, it appears that precise information is not available.
Which answer is it?
A random sample of 17 adult male wolves from the Canadian Northwest Territories gave an average weight x1 = 98.6 pounds with estimated sample standard deviation s1 = 5.6 pounds. Another sample of 26 adult male wolves from Alaska gave an average weight x2 = 88.2 pounds with estimated sample standard deviation s2 = 6.0 pounds. (a) Categorize the problem below according to parameter being estimated, proportion p, mean μ, difference of means μ1 – μ2, or difference of proportions p1 – p2. Then solve the problem. μp μ1 – μ2p1 – p2 (b) Let μ1 represent the population mean weight of adult male wolves from the Northwest Territories, and let μ2 represent the population mean weight of adult male wolves from Alaska. Find a 99% confidence interval for μ1 – μ2. (Use 1 decimal place.) lower limit upper limit (c) Examine the confidence interval and explain what it means in the context of this problem. Does the interval consist of numbers that are all positive? all negative? of…
Suppose that the TSH (Thyroid Stimulating Hormone) levels among healthy individuals are normally distributed with a mean of 3.2 units/mL. Suppose also that exactly 98% of healthy individuals have TSH levels below 6.1units/mL. Find the standard deviation of the distribution of TSH levels of healthy individuals. Carry your intermediate computations to at least four decimal places. Round your answer to at least two decimal places.

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