A set of samples from an abandoned industrial site detected a suspected groundwater contaminant at a mean concentration of 0.045 µg/L with a standard deviation of 0.007 µg/L. How many samples are required to be collected at a confidence level of 95% and power of 90% if the mean background concentration of the contaminant is 0.035 µg/L? О А.З О В. 4 С. 5 O D. 6

A set of samples from an abandoned industrial site detected a suspected groundwater contaminant at a mean concentration of 0.045 µg/L with a standard deviation of 0.007 µg/L. How many samples are required to be collected at a confidence level of 95% and power of 90% if the mean background concentration of the contaminant is 0.035 µg/L? О А.З О В. 4 С. 5 O D. 6

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter7: Statistical Data Treatment And Evaluation

Section: Chapter Questions

Problem 7.13QAP

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A set of samples from an abandoned industrial site detected a suspected groundwater contaminant at a mean concentration of 0.045 µg/L with a standard deviation of 0.007 µg/L. How many samples are required to be collected at a confidence level of 95% and power of 90% if the mean background concentration of the contaminant is 0.035 µg/L? О А.3 В. 4 О С.5 O D. 6
A volume of 250 ml of a 0.05 M solution of a reagent of formula weight (relative molecular mass) 40 was made up, the weighing being done by difference. The standard deviation of each weighing was 0.0001 g. 1 (a) What were the standard deviation and relative standard deviation of the weight of reagent used?
For the determination of iron in used jet engine oil, 30 analyzes with 3 repetitions each were made by atomic absorption method and the standard deviation was found s=2.4 µg Fe/mL. Since this standard deviation value is close to the ϭ value, the iron concentration of 18.5 µg Fe/mL(a) by a single analysis,(b) as the average of the two analyzes,(c) Calculate the 80% and 95% confidence intervals if found as the mean of four analyses.
A young researcher was evaluating a standard method for determining the methylmercury content in blue fin tuna using high performance liquid chromatography (HPLC). She determined the standard deviation (?)(s) for the method to be 0.440.44 ppb and assumed that ?s was a good approximation of ?σ . As a test, she used this method to evaluate the methylmercury content in a National Institutes of Standards and Technology (NIST) standard and determined the unknown amount to be within 0.210.21 ppb (?)(μ) of the known mean with 99% probability. How many replicate measurements of the NIST standard did the researcher perform?
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A clinical chemist obtained the following data for the alcohol content of a sample of blood: % C2H5OH: 0.084, 0.089, and 0.079. Calculate the 95% confidence interval for the mean assuming that (a) the three results obtained are the only indication of the precision of the method and that (b), from previous experience on hundreds of samples, we know that the standard deviation of the method s 5 0.005% C2H5OH and is a good estimate of s.
To test the quality of the work of a commercial laboratory, duplicate analyses of apurified benzoic acid (68.8% C, 4.953% H) sample were requested. It is assumed that therelative standard deviation of the method is sr →  = 4 ppt for carbon and 6 ppt forhydrogen. The means of the reported results are 68.5% C and 4.882% H. At the 95%confidence level, is there any indication of systematic error in either analysis?
How do you find the standard deviation with these calculations?
Can you please fill the rest of tghe data based on the on inforamtion you have and answer Average concentratuon of NaOH Standard deviation of concentration
What is the relative average deviation in the following percent KHP values in ppt? (Enter your answer as a number without units.) 46.89 % 47.51 % 47.92 %
please help find standard devi. and average
What is the relative average deviation in the following percent KHP values in ppt? 46.80% 47.23% 48.03%