(a)
Interpretation:
The counting rate 9cpm is the background counting rate in the laboratory which was measured at the time period of 3 min and it is required that the value of standard relative deviation should be less than the 5%
Concept introduction:
The formula for the standard deviation for the corrected counting rate is given as-
Where,
Relative standard deviation is represented by the following formula-
Also,
(b)
Interpretation:
The counting rate 9cpm is the background counting rate in the laboratory which was measured at the time period of 3 min and it is required that the value of standard relative deviation should be less than the 5%
Concept introduction:
The formula for the standard deviation for the corrected counting rate is given as-
Where,
Relative standard deviation is represented by the following formula-
Also,
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Principles of Instrumental Analysis
- A solution is prepared by weighing 5.0000 g of cesium iodide into a 100-mL volumetric flask. The balance used has a precision of 0.2 mg reported as a standard deviation, and the volumetric flask could be filled with a precision of 0.15mL also reported as a standard deviation. What is the estimated standard deviation of concentration (g/mL)?arrow_forwardTo 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?arrow_forwardA 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?arrow_forward
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- Principles of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning