Bunuel wrote:

If \(x \gt 0\) and \(xy=z\), what is the value of \(yz\)?

(1) \(x^2*y=3\).

(2) \(\sqrt{x*y^2}=3\).

Given \(xy=z\) and asked us to find \(yz\).

For equation \(xy=z\) , multiplying y on both sides

=> \(xy^2\) =\(yz\) or \(yz\) = \(xy^2\).

Then we need to know the value of \(xy^2\) ---> eq 1.

Stat 1: \(x^2*y=3\)

=> y = 3 / \(x^2\) --> squaring... \(y^2\) = 9 / \(x^4\).

Then sub \(y^2\) value in eq 1 , we get the result as 9 / \(x^3\). We are not sure of x value.

This is not sufficient.Stat 2: Given \(\sqrt{x*y^2}\) = 3.

Squaring on both side we get \(xy^2\) = 9.

Then substituting in eq 1 , we get yz = 9.

This is sufficient.Hence correct answer is B.