Volume for a cone is 1/3 pi * r^2*h, where r is radius and h is height. We have diameter = 1/2 radius. Thus, radius = 1.5in. We also have volume is 12 in. Using formula for volume of a cone and plugging in what we know, we have 12 = 1/3*pi*(1.5)^2*h, were solving for h. To get, h= (12*3)/(pi*(1.5)^2), which is approximately 5.0931in, 5 inches