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Correlation after rescaling and shifting variables

Question

If Corr⁡(X,Y)=0.56\operatorname{Corr}(X,Y)=0.56, find the correlation of 8X8X with Y+7Y+7.

Short answer

0.560.56. Adding constants does not affect covariance or standard deviations, and multiplying XX by the positive number 88 scales the covariance and σX\sigma_X by the same factor, so the correlation is unchanged.

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