Let x be a distribution and a is a constant.
mean(ax) = a * mean(x)
sd(ax) = a^2 * sd(x)
I'm only 99.9% sure, so you should go to
http://en.wikipedia.org/wiki/Standard_deviation to check the basic definitions of SD and to see if you work out the two above equations for yourself.
Also, most basic statistic textbooks should have the two above relations buried somewhere inside.