Chapter 2, Problem 10P

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.

A powder was prepared containing 3.00% NaCN and 97.00% NaCl. A sample obtained from that mixture containing 7.374×10^5 particles weighs 10.0 g. Determine the number and percent relative standard deviation of NaCN particles from a sample of the mixture weighing 6.30 g. I need nNaCN particles and %RSD

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)?

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?

The following densities of water were obtained by Student A: 1.07 g/mL, 1.14 g/mL, and 1.13 g/mL. Show how Student A determined the density of water to be 1.11 ± 0.04 g/mL. Calculation for the average = 1.11 g/mL: Calculation for the standard deviation = 0.04 g/mL:

The density of kerosene is 0.810 g/mL and was measured using a hydrometer with a standard deviation of ±0.015. Calculate the volume and propagate the error if the mass of the kerosene is 1.67 g.

Suppose a certain species of fawns between 1 and 5 months old have a body weight that is approximately normally distributed with mean μ=28.6  kilograms and standard deviation σ=3.7 kilograms. Let x be the weight of a fawn in kilograms. Convert the following z interval to a x interval. 2.7 < z Choices x < 18.61 x < 38.59 x > 38.59 x > 18.61 x -38.59

:0.29 µg Cu/mL (s → ơ). The analysis of an oil from a reciprocating aircraft An atomic absorption method for determination of copper in fuel samples yielded a pooled standard deviation of spooled engine showed a copper content of 8.03 ug Cu/mL. Calculate the 95 and 99% confidence intervals for the result if it was based on (This problem requires values in your textbook's specific appendices, which you can access through the OWLV2 MindTap Reader. You should not use the OWLV2 References' Tables to answer this question as the values will not match.) a a single analysis 95% confidence interval = 8.03 + µg Cu/mL 99% confidence interval = 8.03 ± ug Cu/mL b the mean of 5 analyses 95% confidence interval = 8.03 + | ug Cu/mL 99% confidence interval = 8.03 ± µg Cu/mL c the mean of 15 analyses 95% confidence interval = 8.03 + ug Cu/mL 99% confidence interval = 8.03 ± ug Cu/mL

A method for the detection of morphine is used to generate a calibration curve in which the assay response (y) is plotted versus morphine concentration (x, in mg/L). This gives a straight line with a slope (m) of 0.241 and a y-intercept (b) of 0.011, where y = mx + b.  The slope of this line has a standard deviation of ±0.007, and the standard deviation of the intercept is ±0.006.  If the sample from an athlete gives a response of 0.506 ± 0.013 in this method, what is the concentration of morphine in the sample and estimated precision of this concentration?