Question

X = 7 and SX2 = 21. A new variable Y is created by multiplying each X by 3. What are SY and SY2 equal to ?

I do not understand.

Answer 1

I am unfamiliar with your notation. Is X supposed to be the mean of a set of X's? In that case you should have called it X with a bar under it or Xmean. Is SX2 the variance of the set of X's? If you triple all the X's to get a set Y, The new Ymean is triple the value of Xmean, and SY2 becomes 9 SX2 = 189