variance

• Does Standard Deviation Change When You Add or Multiply by a Constant?
  Adding a constant leaves the standard deviation unchanged; multiplying by a scales it by |a| and the variance by a². Proof, examples and the general rule for aX + b.
• What Is the Standard Deviation of a Dice Roll?
  The standard deviation of one fair six-sided die is √(35/12) ≈ 1.708. See the derivation, the formula for any die, and how it scales for sums and averages.