If the standard deviation of X is 15,the covariance of X and Y is 94.5,the coefficient of correlation r = 0.90,then the variance of Y is 7.0.

Question

Quizplus · Accepted Answer

The variance of Y can be calculated using the formula for the correlation coefficient: $ r = \frac{\text{Cov}(X, Y)}{\sigma_X \sigma_Y} $. Given $ r = 0.90 $, $\text{Cov}(X, Y) = 94.5$, and $\sigma_X = 15$, we can solve for $\sigma_Y$ and then find the variance of Y, which is not 7.0.

If the Standard Deviation of X Is 15,the Covariance of X