Question

The following results were obtained for the determination of calcium in a NIST limestone sample: %CaO = 50.32, 50.23, 50.39, 50.20, and 50.43. Five gross samples were then obtained for a carload of limestone. The average percent CaO values for the gross samples were found to be 49.48, 50.10, 49.63, 49.88, and 50.47. Calculate the relative standard deviation associated with the sampling step. Relative standard deviation =

Answer 1

First calculate the standard deviation

For that first get the mean then the difference of each data from the mean and then square the difference

Find the mean of that and then get the square root this is your standard deviation.

The standard deviation of the first set is 0.09915

The mean of the first set is 50.314

% relative standard deviation is 0.09915/50.314 x100 = 0.197%

The next set the samples

The standard deviation of the first set is 0.3918

The mean of the first set is 49.912

% relative standard deviation is 0.3918/49.912 x100 = 0.785%