Two methods were used to measure fluorescence lifetime of a dye. The average result for Method 1 is = 1.382 ns with a standard deviation of s1 = 0.039 and n1= 7. The average result for Method 2 is = 1.346 ns with a standard deviation of s2 = 0.015 and n2= 5. Is there a difference between the two methods at the 95% confidence level using F test?

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.

: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

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.