Question

For the bivariate data r = 0.3, cov(X, Y) = 18, σ_x = 3, find σ_y .

Answer 1

r= 0.3, cov(X,Y) =18, ` sigma_x = 3,sigma_y = ?`

`r=cov(x,y)/(sigma_x .sigma_y)`

`0.3=18/(3.sigma_y)`

`sigma_y=18/(0.3xx3)`

`sigma_y=180/9`

`sigma_y=20`