posted by Emily .
Juan makes a measurement in a chemistry laboratory and records the result in his lab report. The standard deviation of students' lab measurements is 10 milligrams. Juan repeats the measurement 3 times and records the mean (x-bar) of his 3 measurements.
a) What is the standard deviation of Juan's mean result? (that is, if Juan kept on making 3 measurements and averaging them, what would be the standard deviation of all his means?)
==> I don't quite understand this concept...can someone please explain this to me? Thanks! :)