An atomic absorption method for the determination of the amount of iron present in used jet engine oil was found from pooling 30 triplicate analyses to have a standard deviation s = 3.8 ug Fe/mL. If s is a good estimate of o, calculate the 95 and 99% confidence intervals for the result 19.6 ug Fe/mL if it was based on the following criteria. (a) a single analysis 95% confidence interval =  19.6 ± ___   ug Fe/mL 99% confidence interval =  19.6 ±  ___ ug Fe/mL   (b) the mean of two analyses 95% confidence interval =  19.6 ±   ___   ug Fe/mL 99% confidence interval =  19.6 ±   ___   ug Fe/mL (c) the mean of five analyses 95% confidence interval =  19.6 ±   ___   ug Fe/mL 99% confidence interval =  19.6 ±   ___   ug Fe/mL

Using the data below, calculate the correlation: covariance   -0.9 standard deviation(x) = 10.5 standard deviation(y) = 10.4   (calculate to 2 significant figures)

Assume you have an SAR of 0.206 for sample 1; 0.271 for sample 2; and 0.606 for sample 3, what does this indicate?

A mixture of species of A and B is injected into a liquid chromatographic column with length of 20.0 cm. The obtained separation results are listed as follows: Species Retention time (min) Peak Width at Base (min) Non-retained 3.0 A 5.2 0.48 В 5.9 0.56 From the data, the calculated resolution Rs is smaller than 1.5 for A and B when the column length is 20.0 cm, which indicates that A and B are not separate completely. What is the new column length (unit: cm) necessary to separate the A and B species with a good resolution Rs = 1.5? Please keep your answer to one decimal place.