Q1

A scientist obtained the following data for percent lindane in the triplicate analysis of an insecticide preparation: 7.23, 6.95 and 7.53. Calculate the 90% confidence interval for the mean of the three data, assuming that (a) The only information about the precision of the method is the precision for the three data. (b) On the basis of long experience with the method, it is believed that s = 0.28% lindane

Q2

What is the standard error of a mean ; and why is the standard deviation of the mean lower than the standard deviation of the data points in a set?