First we need to find what is the volume of the vase.
Volume of a cylinder we calculated by:
V = r^2*pi*h where r is radius and h is height.
V = 4^2 * 3.1415* 10
V = 502,64 inch^3
Now, since vase should be filled 3/4 of its volume, the volume of water that needs to be poured in is:
Vw = 3/4*V = 378 inch^3