An environmental scientist developed a new analytical method for the determination of cadmium (Cd+) in mussels. To validatethe method, the researcher measured the Cdt concentration in standard reference material (SRM) 2976 that is known to contain0.82 + 0.16 ppm Cd+. Five replicate measurements of the SRM were obtained using the new method, giving values of 0.787,0.758, 0.824, 0.838, and 0.765ppmCalculate the mean (x), standard deviation (s,), and the 95% confidence interval. A list of i values can be found in the Student'stable.X3=PpmPpm95% confidence interval: +PpmDoes the new method give a result that differs from the known result of the SRM at the 95% confidence level?noyes

Given n= 5 X values = 0.787, 0.758 ,0.824 ,0.838, 0.765 95% confidence interval Find mean ? Std…

Answered: An environmental scientist developed a…

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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In experiments to determine the effectiveness of drugs such as anti-fungal ointments that are applied to the skin, the concentration of the drug in a patient’s skin must be measured. The article “Determining Bioequivalence of Topical Dermatological Drug Products by Tape- Stripping” (W. Navidi, A. Hutchinson, et al., Journal of Pharmacokinetics and Pharmacodynamics, 2008:213–220) describes an improved method of measuring that is designed to ensure that all the drug in the skin is recovered. Assume that in an experiment using the old method, the mean amount of drug recovered from a sample of 49 patients was 105 ng with a standard deviation of 20 ng, and that in an experiment using the new method the mean amount of drug recovered in a sample of 35 patients was 117 ng with a standard deviation of 15 ng. Find a 98% confidence interval for the difference in the mean amounts recovered between the two methods.
Listed below are amounts of strontium-90 (in millibecquerel mBq) in a simple random sample of baby teeth. 128, 130, 133, 137, 138, 142, 142, 144, 147, 149, 151, 151, 151, 155, 156, 161, 163, 163, 166, 172 Construct a boxplot and identify the 5-number summary.
A study was conducted to examine if children with autism spectrum disorder (ASD) had higher prenatal exposure to air pollution, specifically particulate matter < 2.5 g in diameter (PM2.5). Researchers obtained birth records of all children born in Los Angeles between 2000 and 2008 and linked these to the Department of Developmental Services records to determine if any of those subjects had been diagnosed with ASD or not. They used the birth addresses given in the birth records to determine the average daily PM2.5 for the third trimester for each child. The standard deviation for PM2.5 among ASD subjects was found to be 34.6 and for non-ASD subjects was 16.8. Assume PM2.5 is normally distributed. 4a. What was the study design? * Randomized Clinical Trial (RCT) * Case Report * Nested Case-Control Study * Case-Control Study * cross-sectional study Cohort Study 4B. What are the null and alternative hypotheses? 4c. What type of statistical test would you use to analyze the…
Natalie conducted a study on the effects of triclosan on three algae populations. She collected an algae sample from three different ponds, counted the number of algae cells present in the sample, and then exposed them to a 5 ppm aqueous solution of triclosan and re-counted the number of algae cells in each sample. Using a paired t-test, she obtained a p-value of 0.083 when comparing the original algae population sizes to the population sizes after exposure to triclosan. Natalie concluded that triclosan is toxic to algae because her data for the three samples showed a trend toward a reduction in population size. What could Natalie do to show a statistically significant effect of triclosan on algae population size? Justify your response.
A survey of 90 recently delivered women on the rolls of a county welfare department revealed that 27 had a history of intrapartum or postpartum infection. Can we conclude that the population proportion with a history of intrapartum or postpartum infection is significantly less than or equal to 0.25? Let alpha = 0.05.
Brink studied the effect of postural change on cardiovascular reactivity for a sample of healthy white and African American men and women. Change in systolic blood pressure (SBP) from supine to standing position was used as the measure of cardiac reactivity in a sample of 842 adults. Supine measurement of blood pressure was taken after participants had lain on an examination table for 15 minutes. Blood pressure was measured five times every 2 minutes using a preset automated blood pressure monitor, and the five measurements were averaged. Participants then stood up, and an additional five measurements were made over another 10-minute period and then averaged. Below is a table describing the characteristics of Brink’s sample. Characteristics of the Study Sample (N = 842) Sample Characteristic Frequency (N) Percentage or Mean (SD) Range Gender Female Male 408 434 48.5% 51.5% Age (years) 842 55.1 (5.3) 44–67 Race/ethnicity White, not Hispanic…
The Amercian Water Works Association reports that the per capita water use in a single family home is 69 gallons per day. A new housing development agency had builders intall more efficient water fixtures and conducted a survey of residents. 36 residents responded and the sample mean water use was 64 galons with a SD of 8.8 gallons per day. At the 0.10 level of significance, is that enough evidence to conclude that these residents surveyed are using less water on average ?
A survey of 90 recently delivered women on the rolls of a county welfare department revealed that 27 had a history of intrapartum or postpartum infection. What is the critical value of z if we need to conclude that the population proportion with a history of intrapartum or postpartum infection is less than 0.25.
A survey of 90 recently delivered women on the rolls of a county welfare department revealed that 27 had a history of intrapartum or postpartum infection. Can we conclude that the population proportion with a history of intrapartum or postpartum infection is less than or equal to 0.25. Let alpha = 0.05
It is believed that a sweetener called xylitol helps prevent ear infections. In a randomized experiment, 165 children took a placebo and 68 of them got ear infections. Another sample of 159 children took xylitol and 46 of them got ear infections. The scientists believe that the proportion of ear infections in the placebo group will be greater than the xylitol group. Test this hypothesis at α = 0.025.
Suppose an experiment finds that people taking a new herbal remedy get fewer colds than people taking a placebo. The results are statistically significant at the 0.01 level. Has the experiment proven that the herbal remedy works?
According to the National Health and Nutrition Examination Survey (NHANES) sponsored by the U.S. government, a random sample of 712 males between 20 and 29 years of age and a random sample of 1,001 males over the age of 75 were chosen and the weight of each of the males were recorded (in kg). Do the data provide evidence that the younger male population weighs more (on average) than the older male population? Use “Y” for ages 20-29 and “S” for ages 75+. It was found that x̅Y=83.4, sY=18.7, x̅S=78.5, and sS=19.0. a) Is the normality condition met for this test? (see picture) No, since the histograms show skewness and outliers . Yes, since both sample sizes are larger than 30. No, since both sample sizes, nY and nS, are less than 30. Yes, since it was stated that the two populations are normally distributed. b)What are the correct degrees of freedom for this test? Group of answer choices 999 1000 1712 1711 711

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