Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Let $X$ be a random variable with a mean of $\mu$ and a variance of $\sigma^2$ and let $Y = aX +b$. Show for non-zero constants $a$ and $b$ that $\operatorname{Corr}(X; Y ) = +1$ or $-1$.

share|cite|improve this question

Use the fact that $$\text{Corr}(X,Y) = \frac{\text{Cov}(X,Y)}{\sigma_{X} \sigma_{Y}}$$

share|cite|improve this answer
is there a way to break apart the equation y= ax+b in order to incorporate a and b into the formula for correlation? – kay Jan 31 '12 at 15:45

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.