Suppose I have a radar gun that can measure velocity with an internal error with a mean of 3 m/s and a standard deviation of 1m/s on that error eg velocity 10 +- 2.8 6 +- 3.1 21 +- 3.2 and so on. Now I want to make a prediction of the future when I get a new radar gun. It will have an internal error of roughly 1m/s How then do I scale the std deviation? by a factor of three? Thanks all!