How do I solve this direct variation question?

Question

If U varies directly as the square root of V and U = 2 wjen V = 9. Find the value of V when U = 4

Answer 1

U=+ksqrV

2 = ksqr9 = 3k

k=2/3

4=(2/3)sqrV

sqrV =3/2 x 4 = 6

sqrV =6

V= 36