Contaminated water: Polychlorinated biphenyls (PCBS) are a group of synthetic oil-like chemicals that were at one time widely used as insulation in electricalequipment and were discharged into rivers. They were discovered to be a health hazard and were banned in the 1970s. Assume that water samples are beingdrawn from a river in order to estimate the PCB concentration. Suppose that a random sample of size 89 has a sample mean of 1.81 parts per billion (ppb).Assume the population standard deviation is o=0.44 ppb.Part: 0 / 3Part 1 of 3(a) Construct a 98% confidence interval for the PCB concentration. Use tables or technology. Round your answers to at least two decimal places.CD:The confidence interval isNOV1WMacBook Air80888DIIDDF2F3F4F5F6F7F8F9F10$&

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Answered: Contaminated water: Polychlorinated…

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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As part of the United States Department of Agriculture's Super Dump Cleanup in the early 2000s, various sites in the country were targeted for cleanup. Three of the targeted sites - River X, River Y, and River Z - had become contaminated with pesticides because they were located near abandoned pesticide dump sites. Measurements of the concentration of aldrin (a commonly used pesticide) were taken at twenty randomly selected locations in each river near the dump sites. The boxplots shown below display the five-number summaries for the concentrations, in parts per million (ppm) of aldrin, for the twenty locations that were sampled in each of the three rivers. River X River Y River Z+ 3.4 (a) Compare the distributions of concentration of aldrin among the three rivers. Use your SOCS. (b) The twenty concentrations of aldrin for River X are given below. 4.0 5.6 5 6 7 Concentrations of Aldrin (ppm) 8.6 5.1 8.7 River X Aldrin Concentration Data 3.7 8.0 5.5 5.3 8 4.6 4.2 4.3 7.3 7.5 5.3 8.2 4.7…
In an assessment of the quality of the electrical power system, one measure of quality is the degree to which voltage fluctuations cause light flicker in the system. The perception of light flicker x when the system is set at 380kV was measured periodically (over 10-minute intervals). For transformers supplying heavy industry plants, suppose the light flicker distribution was found to follow (approximately) a normal distribution with µ= 2.4% and o = 0.4. If the perception of light flicker exceeds 3.2%, the transformer is shut down and the system is reset. How likely is it for a transformer supplying a heavy industry plant to be shut down due to light flicker? ... There is a probability that a transformer supplying a heavy industry plant will need to be shut down. (Round to three decimal places as needed.)
A state-by-state survey found that the proportions of adults who are smokers in state A and state B were 24.5% and 17.7%, respectively. (Suppose the number of respondents from each state was 3000.) At a = 0.01, can you support the claim that the proportion of adults who are smokers is lower in state A than in state B? Assume the random samples are independent. Complete parts (a) through (e). (b) Find the critical value(s) and identify the rejection region(s). D (Use a comma to separate answers as needed. Type an integer or a decimal Round to two devimal places as needed.) %3D Identify the rejection region(s). Choose the correct answer below. O A. z-2.58 O D. z2.58 OF. z2.33 (c) Find the standardized test statistic. (Round to two decimal places as needed.)
A population with μ = 54 and σ = 12 is standardized to create a new distribution with μ = 100 and σ = 20. After the transformation, an individual receives a new score of X = 95. The original score for this individual was X = 51. True or False?
4.12. A machine is used to fill containers with a liquid product. Fill volume can be assumed to be normally distributed. A random sample of ten containers is selected, and the net contents (oz) are as follows: 12.03, 12.01, 12.04, 12.02, 12.06, 11.98, 11.97, 12.02, 12.05, and 11.99. (a) Suppose that the manufacturer wants to be sure that the mean net contents exceeds 12 oz. What conclusions can be drawn from the data (use a = 0.01)? (b) Construct a 99% two-sided confidence interval on the mean fill volume.
Patients with rheumatoid arthritis are at a greater risk of developing osteoporosis. The reasons are not well understood due to the difficulty in qualitatively assessing bone metabolism and mineral content. A researcher measures human calcitonin (HCT) levels in men with rheumatoid arthritis. The researcher randomly selects 43 men with rheumatoid arthritis and measured the mean HCT level of 33.8 pg/mL. Assume that HCT for individuals with rheumatoid arthritis follows a normal distribution with standard deviation σ = 23.6 pg/mL. 5. What is the effect on the interval width if we decreased or increase the confidence level to 90% or 99% respectively? (Hint, create the intervals)
Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 43 male firefighters are tested and that they have a plasma volume sample mean of x = 37.5 ml/kg (milliliters plasma per kilogram body weight). Assume that ? = 7.80 ml/kg for the distribution of blood plasma. (a) Find a 99% confidence interval for the population mean blood plasma volume in male firefighters. What is the margin of error? (Round your answers to two decimal places.) lower limit upper limit margin of error (d) Find the sample size necessary for a 99% confidence level with maximal margin of error E = 2.10 for the mean plasma volume in male firefighters. (Round up to the nearest whole number.)male firefighters
A state-by-state survey found that the proportions of adults who are smokers in state A and state B were 23.1% and 17.2%, respectively. (Suppose the number of respondents from each state was 2000.) At α=0.05, can you support the claim that the proportion of adults who are smokers is greater in state A than in state B? Assume the random samples are independent. Complete parts (a) through (e).
The population mean will always be the same as the mean of all possible X¯ that can be computed from samples of size 21.
Inorganic phosphorous is a naturally occurring element in all plants and animals, with concentrations increasing progressively up the food chain (fruit < vegetables < cereals < nuts < corpse). Geochemical surveys take soil samples to determine phosphorous content (in ppm, parts per million). A high phosphorous content may or may not indicate an ancient burial site, food storage site, or even a garbage dump. Independent random samples from two regions gave the following phosphorous measurements (in ppm). Assume the distribution of phosphorous is mound-shaped and symmetric for these two regions. Region I: x1; n1 = 15 853 1,549 1,230 875 1,080 2,330 1,850 1,860 2,340 1,080 910 1,130 1,450 1,260 1,010 Region II: x2; n2 = 14 538 808 790 1,230 1,770 960 1,650 860 890 640 1,180 1,160 1,050 1,020 (a) Use a calculator with mean and standard deviation keys to verify that x1, s1, x2, and s2. (Round your answers to four decimal places.) x1= ppm s1= ppm x2= ppm s2=…
Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 44 male firefighters are tested and that they have a plasma volume sample mean of x = 37.5 ml/kg (milliliters plasma per kilogram body weight). Assume that ? = 7.40 ml/kg for the distribution of blood plasma. (a) Find a 99% confidence interval for the population mean blood plasma volume in male firefighters. What is the margin of error? (Round your answers to two decimal places.) lower limit ? upper limit ? margin of error ?
Inorganic phosphorous is a naturally occurring element in all plants and animals, with concentrations increasing progressively up the food chain (fruit < vegetables < cereaise nuts < corpse). Geochemical surveys take soil samples to determine phosphorous content (in ppm, parts per million). A high phosphorous content may or may not indicate an ancient burial site, food storage site, or even a garbage dump. Independent random samples from two regions gave the following phosphorous measurements (in ppm). Assume the distribution of phosphorous is mound-shaped and symmetric for these two regions. Region It x n, 15 857 1,551 1,230 875 1,080 2,330 1,850 1,860 2,340 1,080 910 1,130 1,450 1,260 1,010 Region III xi n 14 542 B06 1,230 1,770 790 960 1,650 860 890 640 1,180 1,160 1,050 1,020 A USE SALT (a) Use a caiculator with mean and standard deviation keys to verify that a and s (Round your answers to four decimal places.) ppm ppm ppm ppm (b) Let , be the population mean for x, and let be the…

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