Step 1

Given: \(Cov(X, Y) = 0.9\)

\(Var(X) = 4\ \&\ Var(Y) = 9\)

The coefficient of correlation is given by

\(r=\frac{Cov(X,Y)}{\sqrt{Var(X)Var(Y)}}\)

\(=\frac{0.9}{\sqrt{4\times 9}}\)

\(=0.15\)

Step 2

Hence the correlation between \(X\ \&\ Y\) is 0.150.